The only Tea Room in Venice, Beatrice is a tranquil oasis of nearly pure quiet in Dorsoduro. They have more than 50 varieties of specialty teas which can also be paired with amazing cakes from Vizio Virtu, one of the best pastry shops in Venice. Enjoy these in the peaceful garden or intimate interior.
The only problem you could have there would be finding a good reason to ever leave. Fortunately, that might not be too much of a problem because they also have a B & B just up the stairs!