Logistics of 1 night in venice with car before early flight

If the airport hotel has a shuttle to the airport, I'd go with returning the car at the airport Friday, taking the bus to Piazzale Roma and the vaporetto into whatever you have time to see in Venice, then back to the airport, shuttle to hotel, overnight, and Saturday early AM shuttle to the airport. That minimizes the risk of missing the flight and saves you the cost and trouble of keeping the car overnight when you're not using it.

If the hotel doesn't have a shuttle to the airport, you'll need to keep the car to get there Saturday morning. You could try parking it at Piazzale Roma and spending the night in Venice, but I'd see that as risking being late for the flight. The fewer things you have to do Saturday AM the better.

I wouldn't be concerned about a late-night bus ride from Venice to the airport from a safety standpoint, but you'll want to check what hours the buses and vaporettos operate.

Have you ever been to Venice before?

If you have not, even eight hours in Venice is worth it. Returning the car might save you more than half the cost of a private water taxi back to the airport in the evening. Getting rid of the bags is an issue, I can see.

My first time in Venice was about 8 or 10 hours, on a business trip that otherwise would not have included Venice. It was thrilling, and very worth it.

If it was me, I'd drive straight to an airport hotel that has an airport shuttle. Check in and drop your bags there. Odds are your room won't be ready yet. Then drive to the airport and drop the car. Take the bus into Venice and do your thing for the afternoon and evening. Bus back to airport, and shuttle to your hotel. I think the last bus to the airport is sometime after midnight.

Then in the morning you don't need to worry about gassing up the car or dropping it off. Just shuttle to the airport.

If your flight out of Venice is at 6am, under the best of conditions, you're up at 3
to head for the airport by 3:30-3:45-ish. Having to do anything more than get to
the airport means you might as well pull an all-nighter and not get a hotel.

I think CJean has the right idea. If you can return the car in Mestre, driving straight
there, dumping the car, and going into Venice from there might also work. Or
drop the car at the airport and take the bus to Mestre and drop off luggage. There's
frequent bus and tram departures into Venice.

Many will shun Mestre as a place to stay, but for one night with a 6am flight the next
morning, I don't think it makes much difference.

You can drop the car at Piazzale Rome on Friday—-most rental car companies have offices there. Then book a hotel right there (Piazza Roma) and you are IN Venice. Ask them to book a taxi to pick you up at 3:30 am the next morning. We have stayed at the Marriott AC Hotel and Hotel Arlecchino for this purpose.

We were there last September with our son and his family, and they had a 6 am flight like you. We all stayed at Hotel Arlecchino (son’s family was in their quad room and we had a double, both with canal view.). They actually chose to book the taxi for 4 am, and that worked out fine, much to my relief. I have long ago given up trying to advise my adult son what to do!

If you would rather stay at an airport hotel, you could still drop the car at Piazzale Roma, stopping first to drop off your luggage at the hotel. They should be happy to hold it for you until check-in. Then you will be in Venice and can stay as late as you want, after confirming that whatever form of transport you will use to return to the hotel will still be running.

If you choose this option, also confirm that the hotel shuttle will start running early enough in the morning.