Quick update. Had a great time on the Viking Sea. As I suspected (thanks for the helpful comments!), guests are not dropped at Fusina at disembarkation. For those not going to the airport, Viking takes you (via a 25 min bus ride) from the Fusina port to the old Marittima port in Venice where you collect your baggage and can easily arrange transport to wherever you need to. Beware getting info from the Viking reps, several folks on the cruise got conflicting info from them. It all worked out for us as we had pre-arranged a pickup with our hotel at Marittima.
Great trip. Thanks for the help!