We just arrived in Chiang Mai after spending approximately 18 hours in Bangkok. We stayed on Khaosan road and, despite not getting to our hostel till 2am, still managed to take in some of the action on the streets. Of course, I had to sample some of the street food because it is sooo cheap and I know that eating should be driven by hunger, not availability, but sometimes I can't help myself. Also, Khaosan road has, in my opinion, the best deal in Bangkok - pad thai with egg for 30 baht ($1).
Probably the best pad thai you will ever eat in your life and definitely worth every baht. You know you're in Thailand when you're eating pad thai, in a tuk tuk, on the way to a ping pong show.