A visit to one of the floating markets is a fun way to do some shopping and eating while supporting local vendors and observing local commerce in action. but there are others that make for a nice authentic travel experience. You'll need to get up early to visit a floating market, as vendors are out in their long wooden boats first thing in the morning with their goods, fresh fruits, vegetables, spices, and tasty dishes.
There are several floating markets near Bangkok, Amphawa and Damnoen Saduak being among the most popular. You can go it alone or join a guided tour, which can include visits to local houses and shops.