There are quite a lot parking places in Venice, but all very expensive. Near parking there is a Vaporetto water boat bus station, it's best to get one way ticket to Piazza San Marco, and than you walk through the city back to parking. It's nice if you go through small streets that are not to crowded, but you can see beautiful buildings anyway. You can go on St. Mark’s Campanile, bell tower, elevator is 8€/person, it’s very crowded up there, but the view is really nice.
Read about Venice on my blog →