I'm in Thailand (Kan'buri) right now and have just visited Rose Garden within the last couple of weeks. It's a nice place, a big park showing houses built in different traditional Thai style, but the main attraction is the afternoon show which takes you through a quick trip in different Thai cultural lifestyle events such as a Thai wedding, Thai dancing from different parts of the country, real sword fighting, Thai boxing, elephants working, and more. You may also have the chance for a short trip on the elephants back afterwards.

It's a perfect combination to visit the Floating Market early in the morning (beware you are not ripped off there, prices are really higher there than many other places), and then visit Rose Garden on the way back in the afternoon, and most tour agencies are actually organizing this as a combination.

Have you been to the Saturday/Sunday Chatuchak Market, if not it might be an option. Chinatown and the Bangkok Flower Market might be other options. I'm pleased to know that you were happy with your last visit to Kanchanaburi and are planning to come back.