I wouldn't restrict my hotel search based upon proximity to the cruise ship terminal or eas of access from airport. As long as you select a hotel with convenient water taxi access or near a vaporetto stop, Piazza Roma wil generally be within a half hour. Piazza Roma would be where you pick up the free shuttle to the cruise terminal. There are some large hotels near St Marks that are reasonably priced. For perspective St. Marks would be about a half hour walk to the Rialto bridge/market. We normally stay in the Cannaregio district which is centrally located but quiet. I would recommend taking a water taxi from the airport (about 120 euro) as well as a water taxi to Piazza Roma (abot 60 Euro). You can make water taxi arrangements online. The vaporetto, while cheap is crowded and would be difficult with luggage (plus one is technicly restricted to one piece of luggage).