Working backwards, i.e. getting from Venice to VCE airport, you will likely take an Alilaguna transport. Please note that the Alilaguna line is different from the regular vaporetto lines. Specifically look for the Alilaguna stops; they do not have as many options for where to pick it up. Actually, the first question should be what time is your flight out? Looking at the Blue Line Alilaguna, for example, looks like earliest to get you to the airport is 5:10, then the 15 minute walk from the dock to the airport entrance.
The hotel Ala that others have suggested looks like it is quite convenient to the S. Maria del Giglio stop on the Vaporetto, but you will also need to consider how you are getting from the ship to pick up the vaporetto to ride to S. Maria del Giglio. And also on departure morning, may need to look at the regular vaporetto schedule to get to the closest Alilaguna stop (probably San Marco Giardinetti ACTV Fermata/Stop, Riva degli Schiavoni, although google maps shows it a 7 minute walk which means probably more like 15 minute walk with bags if you go the walking to Alilaguna option.)
So, after typing out all of these thoughts, I think if it were me and I had real luggage, I'd do a private taxi to the airport. Your hotel can arrange this. Especially if the flight time is prior to 08:00 AM.
Not sure what time of year you will be visiting Venice, but you may want to look for an app that will alert you to Acqua Alta water levels and warnings. Other misc. pieces of advice for La Serenissima are to pack as light as possible (maybe a challenge with the cruise), take a flashlight, and familiarize yourself with your surroundings via googlemaps street view a little bit ahead of time. I have a trip report from Venice from 2018 that gives the basis for these advices :)
