I've been in Chiang Mai for nearly 3 weeks and have been taking in the city bit by bit whilst learning the art of Thai massage at Jera massage school, close to Chiang Mai gate in the old city. You can read more about my experience of Thai massage here, and I can totally recommend them if you want to learn for yourself.

With numerous markets, hundreds of temples and many agencies offering tours and courses, there is so much to do here. It's more laid back than Bangkok and once you get under the skin of local life there is so much more than most tourists ever experience.
 
I'm not suggesting I've covered it all, but I do now have a reasonably good list that excludes some of the more obvious and touristy things that everyone seems to opt for. I've condensed it all down into the following categories, but there is so much info on the web, so I've tried to keep it useful and share with you my experiences/recommendations.

 1. Temples

With more than 200 wats (temples), you can't visit Chiang Mai and not visit a few of them, as religion is one of the most important parts of the lives of Thai people. However there are so many to choose from, so where should you start? Firstly make sure you cover your knees and shoulders when you visit them (I can't stand it when tourists are purposely disrespectful, surely everyone knows this by now?!); here's my top 5 in no particular order:

Wat Chiang Man - has to feature on the list as it is apparently the oldest wat in the city. More importantly it houses 2 important Buddhas inside the building to the right of the entrance, one of marble and the other crystal, although you do have to look closely to see them and you may leave a little disappointed.

Wat Chedi Luang/Wat Phan Tao - The first houses a chedi which is partly ruins following an earthquake (or the war with the Burmese?). The 'Emerald Buddha' in Bangkok's Wat Pha Kaew once sat here but has since been replaced by a jade replica. The highlight here has to be the 'monk chat' where you can find out about Buddhism and ask questions about anything you like whilst they practice their English on you, there are other temples where you can do this but here it's positively encouraged. 

Wat Phan Tao is sited directly next door so worth poking your head into. It contains a wihaan (hall) of teak and is a slight contrast to Wat Chedi Luang, in terms of size and the warnings about tourist scams?!

 Wat Phra That Doi Suthep - everyone will be able to point you in the direction of this temple which sits 11km North West of the city, on a hill. You don't need to take a tour here, just get a Songthaew (shared taxi), which you can negotiate to approx 100 baht (£2/US£3) per person, plus there's a 30 baht entrance fee. Don't let the cost or distance put you off, as although this is one of the few temples you have to pay to visit, it is totally worth it and sits at the top of my favourite temples list.

You have to climb over 300 steps up the Naga Serpent or take the tram for a small fee when you arrive there, but the views that greet you are rewarding, as are the numerous things you can participate in inside the temple, just make a small donation for each of them:

• Fortune sticks - you will find these in a number of the covered 'shrine' areas inside the temple, usually a pot with wooden sticks in. I unfortunately misunderstood on my first attempt what you do with these, and picked a stick out confidently, then headed to the definitions of the numbers - consequently I received a shocking fortune of extreme bad luck (#4). I later watched one of the locals shaking the sticks until one fell out onto the floor and realised my misfortune was just a case of getting the selection method wrong, so re-did it a second time, receiving number 28 for my efforts and thankfully a much more positive forecast.

• Monk blessing - track one down to give you a blessing and a bracelet of 'string', some chanting (by the monk, not you) involved.
• Oil pouring on your Buddha image - you will need to determine which Buddha image reflects the day of the week you were born. Note that Wednesday has 2 as this is Buddha's birthday, for the afternoon there is a Buddha with animals - which I can verify is correct as it's when I was born! Once you have the right Buddha, just pour oil over the lotus flower/flame whilst making a wish (I think?).
• Walking around the stupa - do this 3 times clockwise for good luck - no donation necessary.
• Golden elephant - I didn't realise this at the time (looked it up afterwards), but apparently lifting it with your little finger whilst making a wish is good practice and if you lift it a second time without a problem the wish will come true?
• Yellow prayer cloth - a large roll of yellow material is situated near the entrance for prayers and good luck wishes to be written upon, think this then ends up as a cover round the base of the stupa.

Visit this temple on a buddhist holiday and chances are it's so crowded you will get in for free, at least I did on Visakha Bucha Day, or should I say 'night' (I arrived just after midnight!). See my other post for more details - Pilgimage for Visakha Bucha, Buddhist holiday. 
 
Wat Jedlin / Wat Nong Chalin - this is the same temple but goes by a number of names. Featuring in my top 3 this one has a tranquil setting with a large pond where you can feed the cat fish, or chat to passing monks (I was caught there for over an hour chatting away!). Locals come here regularly to release cat fish into the pond which I understood from the monk I spoke to, is something to do with good luck for weddings, but I can't find anything about this on the web so am unsure if it is just a story - however I did see a lady doing this whilst I was there, so it definitely happens.
 
 Wat U Mong - you will need to get a songthaew out to this one or a tuk tuk, depending on whether you are alone or in a group as the former tend not to head out that far unless it's worth their while. This temple is hidden away in a wooded area and is completely unique. There's a lake where you can feed birds or fish and it's not at all touristy, at least it wasn't when I visited just before sunset. The highlight here is the labyrinth of tunnels which were apparently built to contain a mentally deranged monk, but the whole site was deserted around 1900 and did not becoming functional again until 1948.

2. Markets

The famous night market is supposed to be better than the ones in Bangkok, but after several visits here I found it much the same as every other market and extremely repetitive (although this does help with bargaining as there is always another stall selling the same thing). Whilst you are there stick around until 9.30pm and go along to the lady boy Cabaret show, which is free and actually so good I had to return to see it a second time!

I much preferred the walking street markets on Saturday and Sunday evenings, namely for the food stalls (cheap and tasty) as well a much more variable stock of products, most of which are clearly hand made by the stall owners. The market on Sunday was my favourite, and definitely the largest of the 3 markets, taking a few hours to trawl through - but it's a great way to spend the evening and for dinner, although it can get crowded.

There are numerous other markets selling wares around the city, you can buy just about anything very cheaply in most of them, but my favourite was the Talat Warorot (located close to the main night market but open during the daytime), as there were a few craft shops and opportunities to purchase cheap supplies for my scrapbook :).

If you take a cookery class there is usually a visit to one of the many local produce markets to purchase ingredients, so also a good way to see what you can do with everything.

3. Food and drink

The best local speciality, is without a doubt khao soi. A delicious noodle soup that is iconic in Chiang Mai and often called "Chiang Mai noodles". It's a coconut milk based curry soup with egg noodles, served with a variety of condiments including, sliced shallots, chilli paste and lime wedges, sprinkled with deep fried noodles. Try the chicken or beef options, both absolutely delicious.

Choosing to move accommodation after my first couple of days, I've been staying close to the Chiang Mai gate food market, which of course I eat at almost every night. The stalls are varied and although a lot of them do not have English menu's or speakers, you can usually point to what you want and for the price (a typical meal of a dish plus rice will set you back about 30 baht: less than £1/US$1) you can always purchase something else if it isn't to your liking. During the daytime and equally intriguing market can be found here, but more produce rather than cooked meals.

I've become completely addicted to mango shakes whilst here and try to limit myself to just one a day, but the Pa fruit shake stall located at the Chiang Mai gate market has resulted in my one a day being 'plus one of these as well'! Famous and featured on CNN, I stumbled across this only recently... it's just a case of picking a fruit and letting the stall owner select a combo to go with it; don't try these shakes before any other or everything will always be 'not as good as a Pa fruit shake'!
 
4. Parks and waterfalls

Getting away from the dusty old city and tourists found me wandering to Buak Hart Park on the South West corner of the old city. It's a very well maintained park which is a great place to relax or read a book. It gets busy in the evenings and at weekends with activities such as keep fit (near the fountain around 6pm) and it's popular with runners, probably because it has a track marked out to keep tabs on your distance covered.  

There are tours to caves and waterfalls offered at most tour agencies around the city, but if you want to do something that isn't on their lists and tends to be visited by locals and a limited number of tourists that find out about it, then 45 km's from the city is Buang Tong waterfalls, also nicknamed the 'sticky waterfalls'. The water source is from the rainbow or 7 colours spring, and contains a significant amount of calcium carbonate which over time becomes deposited on the rocks, creating a non slip carpet which you can climb down and up fairly easily (if you avoid the green or mossy patches). It's absolutely beautiful here and there's no entrance fee or tourists (if you are lucky). Bring a picnic and your swimming shorts. I recommend climbing with a t.shirt and shorts in case you slip and because you will fit in with the locals better and not stand out!

Lake huay tong tao located about 12km North West of the old city is actually a man made reservoir, but it's time as a 'lake' within a park is some what well established as a place to visit and relax, although not that well known to tourists. The entrance fee is just 20 baht, which will allow you access for the full day, and then you can 'hire' one of the restaurant bamboo huts if you buy drinks or something to eat and hang out in the shade. There are often festivals here and it's a popular filming location. If you just want to get away or want to watch a perfect sunset over Doi Suthep (hill) this is the spot, but note that getting here can be pricey if you don't have your own transport. 

5. And finally... a few useful tips

• Dress appropriately. T.shirts and shorts are fine (except in temples) but if you pay attention to the locals, bikini tops and bare chests should be left for the beach, not here. Cover shoulders and knees in temples and take off shoes when entering a building with Buddha images inside (just in case you didn't get it the first time!).
• Don't step on a bank note (to avoid it blowing away) or deface anything associated with the king, and be aware that the national anthem is played in public places at 8am and 6pm every day - so stand respectfully/still with everyone else. I found this out whilst at the walking market and felt really uncomfortable when I realised what was happening!
• Avoid tying your shoes to the outside of your bag - I'm not sure exactly why but someone told me this along with the bank note point and also it's in the Lonely Planet.
• If you don't already know, it seems a lot of people don't! Don't pose with a Buddha and don't get a tattoo of one, both these actions are considered extremely disrespectful by Buddhists.
• Stay in the old city area if you want cheap accommodation and to be closer to the food market (and my favourite fruit shake stall) and with an easy walk from the temples. Stay outside nearer to Thae Pae gate and in the direction of the night market if you want to be near the nightlife, night market and more expensive (still cheap) restaurants and shops.  

Even after almost 3 weeks, I haven't seen it all. These are my must do's next time:

• Doi Inthanon National Park (highest spot in Thailand).
• Trekking to local villages
• Mahout training - still unsure about this given recent research on the treatment of the elephants;
• Oil massage course;
• Yi Peng and the lantern release at Mae Jo;
• Bo Sang handicraft centre;  
• Paper making or batik making experience.