If you have some time left over, make sure you take a vaporetto (public boat service) to one of the smaller islands to experience a unique atmosphere away from the main tourist traffic.
The three islands of Murano, Burano and Torcello are particularly famous - rich in handicrafts and famous for their historical monuments.
Murano is the largest island in the lagoon after Venice itself, located just 1.5 km from the centre, and has been a traditional glassmaker since the Middle Ages. The glassmaking workshops allow you to visit and see the entire production process in person, for more details on glassmaking visit the Museum of Glassof course, there are the ubiquitous shops with typical local glasses, chandeliers, pendants and other souvenirs. In addition to blown glass, they also create beautiful glass ornaments made of coloured glass flowers - millefiori (=a thousand flowers).
Another of the Venetian islands, Burano is famous for its typical lace and the sweets of the local confectioners. At first glance, however, the incredibly colourful facades of the houses along the canal catch the eye.
The most beautiful island in the lagoon is said to be called Torcello. The town, with its numerous churches (the oldest dating from the 9th century), cathedral and palaces, was once a major centre for wool processing.