Zatters is the long walkway all along the back of Dorsoduro which has wonderful views across the wide Giudecca Canal over to the island of Giudecca. There are several cafes and restaurants along here which cater to locals and tourists alike. The one I recommend is Laguna which is opposite the Zattere vaporetto stop. It is perfect for a glass of prosecco and people watching (closed on Wednesdays).