Beyond the tourist activity of Southern Thailand, Chiang Mai is the northern city everybody tells you to visit. However it has not so much: temples and markets, mainly the same that can be found in any other Thai town but with night life due to the tourism and quite more quiet and not so chaotic like Bangkok.
Every Sunday is held the Sunday Walking Street Market, just a market more expensive where you can find anything. Just tourist stuff in my opinion, for walking a bit over there. I recommend you the Warorot Market however, much more local, almost no farangs there and it’s everyday.
This city is a good place to be relaxed. In fact, I had there my first Thai massage which was in a local where the masseuses were ex-prisoner women. In Chiang Mai the prisoner women are taught how to give massages to have a job after the prison. My massage was awesome