Cultural capital of Thailand, an ancient walled city with fabulous shopping, you must see the Night Market and Sunday Market. You can still see the full size moat surrounding the old city, and everywhere you look there are beautiful Buddhist temples.
It's not as busy as Bangkok, or as searingly hot as the Islands, which I find to be a big plus!! The night life is good but not superb, however there are enough bars, discos and live music venues to keep you going.
The sex trade is basically restricted to one street and is easily avoidable, talking about avoidable, avoid Chiang Mai during March, a thick smog descends from the crop burning by the hill farmers, not good.
Otherwise it is the holiday of a lifetime, waterfalls, zip lines, elephant trekking, snake farms, tiger temple, motor cycling, trekking, shopping, swimming, Muay Thai boxing, fitness training, fabulous scenery, Doi Su Thep temple, the food, the fishing, the fish!! The people, the atmosphere, the festivals...superb