Ayuthaya has some of Thailands best (and most hyped and touristed) ruins. It is also a pleasant little town if you prefer that to the rush of Bangkok.

One note - we stayed @ the Krungsri River Hotel, which is very convenient to the train station but on the wrong side of the river for the tourist stuff and the restaurants, and the only way across is a giant highway bridge with no sidewalks, thus any time you want to go anywhere you enter the tuk tuk/saamlaw gauntlet - you will have to negotiate the price of a ride. Lots of the guys are fair enough with you but some aren't and this can be stressful wen you just want to get something to eat and wish you cold walk but know you can't. I had an altercation with one guy who told us one price and then asked for almost double when we got to our destination - feigning misunderstanding. After some heated argument we met in the middle and I realized we were fighting over something like US $2, but mostly I resented being taken advantage of.