I am happy to help hold your hand, Nancy. 🍀
We have spent a lot of time in Venice, most recently this past September with our son and his family (my twin grandsons, age 11). They chose Venice to fly home from after our time in the Dolomites, and only had 2 nights. I helped plan their one full day there, and chose a hotel close to Piazzale Roma to make it easy for them to get to the airport for an early flight (6:30 am). Their hotel booked a taxi for them for 4 am and that all worked out well.
I have some fairly strong opinions about transport modes around Venice—-for example, I would be leery of planning to catch the Alilaguna to the airport at certain stops on the Grand Canal (San Stae and Giglio). When we last took the Alilaguna, we boarded at Rialto and the boat filled up right there. They had to leave people standing on the dock with their luggage at the stops after that. I have no idea how long those poor folks had to wait for another boat, but I certainly felt sorry for them. Maybe that was an unusual situation, as we were in one of their smaller boats, but it just made me wary of the Alilaguna in general. For that and other reasons I do not recommend the Alilaguna any more.
I won’t go into more detail on hotel location, sightseeing, and getting to the airport until we know what time your flight departs. Have you booked that yet? If not, do heed Joe’s advice and avoid the early morning departures. The Venice airport can be very crowded in the mornings, especially during cruise ship season, and the lines to check bags in particular can be very long. Three hours in advance is the recommended time if you are boarding a flight heading to the US, or even a flight to LHR or other airport to connect with a US-bound flight.
I took a quick look at British Airways (they show American Airlines too) and noticed there is an AA flight departing at 12:15 to Philadelphia, where you have 3 hours before the connecting flight to Seattle, arriving here at 21:33. That is pretty ideal in terms of departure time and connection time. The arrival in Seattle is a bit late, but at least you can just go straight to bed. There is a British Airways departure from VCE at 12:45 that gets you to Seattle earlier, at 17:45, but the connection time at Heathrow is only 2 hours, and after our experiences over the last 3 trips to Europe in 2022 and 2023 I would not be comfortable with only 2 hours before the long-haul flight back to Seattle.
I am sure there are other airlines with comparable departure times as well, so look around and do not be lured into a bad flight by a low price.