I can't recommend Casa Martini enough! Ambra was the best Airbnb host we've ever had. Incredibly helpful and went out if her way to make sure we had a great stay. Got example wanted to go to the Lido beach one day and she dropped beach towels off that night. We also had a last minute change in dates and she made it possible to come a bit earlier. Lots of small touches like that plus always helpful if we had questions or needed recommendations for places to eat or things to do.
The apartment itself is great. Very clean and updated. Comfortable bed. Lots of space. And the location is fantastic. We loved staying on Giudecca. It really has a neighborhood feeling. Especially if you want something a bit quieter. The park right next door was great too since we had two small kids. I hope it doesn't become too popular though. You will need a vaporetto pass. There are no bridges.
I highly recommend this place and wouldn't stay anywhere else if I go back to Venice!