I agree with Priscilla -- Venice is one of my favorite cities to just wander around. Another option with a little extra time there is to take a vaparetto or water taxi over to the island of Murano. If you have any interest in world-famous Murano glass, you can get a demonstration at one of the glass factories and browse the many shops with glass works of every size, shape, color, style and use. We spent a couple hours there, stopping for a nice lunch at a restaurant on the water.
-- Eric
