Bangkok's tourist guetto. Khao San Road has all what you may desire.

Kanchanaburi a few hours away by train has the lazy river Kwai and the most famous bridge.

Chiang Mai up north has a somewhat slower pace than Bangkok. Indeed a very relaxing city to catch your breath after a long time on the road.

Thailand is a place you would want to go, with no expectations, cause the advertisement is getting old.