Hi there,

the floating market is called damnoen saduak. Go early in the morning before the crowds, or else, you will be caught in a sampan jam.

Places to see :
- grand palace, wat pho & wat arun
- golden mount temple - i have not been to this one, maybe next trip
- dhammakaya cetiya - also havent been to this one
- khao san road - go for the food and feel of backpackers area
- if you do miss chatuchak, which is only open on sat & sun, you can go to suan lam night market, which is more organise and not as crowded as chatuchak
- if you have time, go to ayuthaya, it's unesco world heritage site
- go to chinatown
- you can even go to kanchanaburi, where you can visit bridge over river kwai and erawan fall, but it's a bit distance from bangkok

if i can remember anyplace, will let you know.