Chang Mai, in northern Thailand, was once a quaint provincial town that has grown immensely and has become over touristed. There aren't a lot of sights in the city, but it's a good base from which to go trekking. Flights, trains, and buses from Bangkok come and go regularly. The night market is famous, but I found it underwhelming. From here you can work your way back to Bangkok and explore small towns that have old, historic sights.
WHAT TO DO:
You may as well go on a trek, since that's why most travelers come here. Most are for 3 days/2 nights, but you can find longer ones. Activities include an elephant ride, a bamboo raft adventure, meeting the hill tribes (who have been spoiled by stupid Westerners giving the kids cash and candy!), and great hiking. Ask around throughout your trip about good tour agencies, because this information always changes. Shop around and compare trek prices because you'll find beg differences. If you feel someone is ripping you off, trust your gut instincts and go elsewhere.
WHAT NOT TO DO:
Stay away from drugs, as you should anywhere in SE Asia! I've heard stories of tourists getting scammed and ending up in a local prison! Our trek was booked through Victoria Tours, and I wouldn't recommend reserving a trek through them.
WHERE AND WHAT TO EAT:
Restaurants are scattered all over the place: look around Kotchasan Road and in the center of town in general, near the Night Market. Try khao soi , a mix of curried chicken with wheat noodles.
WHERE TO STAY:
There are several guesthouses around the Night Market. A clean room should cost about 5 dollars a night, depending how weak or strong the baht is. One decent place is the Night Bazaar Guest House, 89/2 Changklan Road (053-27-1946).