Amphawa is the lesser known of the two "floating markets" to the southwest of Bangkok, the other being Damneun Saduak, and it has quite a different atmosphere. This market is almost entirely visible by walking, as the market lines the canals with walking paths in between and is much more popular with Thais so the goods available are different and the asking prices more reasonable.
There are a few places that you can hire a boat to cruise along the market and nearby river, with trips to see the glow worms being very popular (although they're often shy, what with all the boat noise). Many of the guesthouses can also arrange trips to or from the market by boat if required.
The market is mainly active in the evening, which makes a combined trip to Damneun Saduak a good option (as it's an early morning market). Come down in the afternoon, visit Amphawa in the evening the get up early and head off to nearby Damneun Saduak, beating the later tourist rush.
"Homestays" are a popular option here, although many are more guesthouses-in-traditional-houses than true homestays, it's still a good experience. Lots of these are only marketed to Thais and finding information in English can be difficult, but Google Translate should get you far enough to make a reservation if required.