Lido Island
Our hotel was on Lido Island, not in Venice. (We couldn't find any vacancies in Venice.) In a way it was nice because it was away from the crowds, making it more quite and romantic, plus we had a nice beach. On the other hand it was a little inconvenient to have to take a shuttle boat back and forth in the morning and evenings. The hotel itself was very nice, although we really weren't there very much.
Lido Island is very narrow (a block or two), one side facing Venice, the other the Adriatic Sea. It is comparatively long though -- probably about two miles. The one day we stayed on the island, Sunday (since many places would be closed anyway), it was cooler and rained some, so we never really used the beach -- just walked along it.