Last year we stayed in Hotel Santa Marina located in a quiet Campo near the Rialto bridge. The service was good and friendly and the water taxi leaves you at the back corner.
This time, in September, we will be staying at the Best Western Hotel Ala. Very near Plaza San Marco. At the end of this campo you can take gondola rides, water taxi leaves you at the back door and has a few restaurants around. A friend stayed there last year and says the service is excellent.