Where to stay for 3 nights before our Venice tour begins

Venice is charming and magical. To experience the mornings are evenings you need to stay in the old town. There's no charm at the airport, and it's a hassle getting into Venice each time. Don't you want to relax midday and go back to the hotel after exploring the canals? The mainland is not close to as charming as Venice itself. Enjoy your trip!

Oh no, don’t stay near the airport! Venice is magical!
Our last visit we stayed at Hotel Ala. it is super easy to reach from the airport and is in the centre of Venice. On a previous visit, we stayed in a RS recommended hotel and it was fine but nowhere near as nice as this one. Breakfast was excellent and our lovely, air conditioned room with balcony overlooked a canal with gondolas floating by beneath.
With your three days, you can check the cruise ship schedule and if there is going to be a lot of passengers in dock, go out to Murano or Burano or a different island. You will be away from the crowds but still experiencing the magic of Venice.
You could also just stay early in the RS hotel. I’m sure that would be central, also. Anywhere but by the airport!

I would definitely take a water taxi and stay in Venice your first night. If you know where your tour hotel is, then maybe pick a different neighborhood to stay in those first three nights.

I did pretty much the same as you, only my VCE landing was late at night. I spent that first night at a hotel near the airport, then took the bus and vaporetto to the tour hotel where I had a room for three nights before the tour started. I spent those days seeing everything I could that wasn't on the tour schedule -- Frari Church, San Giorgio Maggiore, Salute, Naval Museum, Correr Museum, Ca'Rezzonico, Ghetto, and lots of wandering. I bought a 3-day vaporetto pass which was a very good investment. (Sometimes it's easy to get on the vaporetto going the wrong way if you're not paying attention. That's an expensive mistake if you just bought a ticket, but a fun little adventure if you have a pass.) On one of the days I took the train to Padua and saw the Scrovegni Chapel, the Basilica, and other sights. That was an easy and worthwhile day trip. But there's plenty to see in Venice for your whole three days.

If you've been flying the night before and all day you'll be plenty tired at 6:00, but I'd say go ahead and get into the city, preferably the tour hotel if you can arrange that. Make it an early night. You'll thank yourself in the morning when you wake up in this beautiful city with time to enjoy it and get used to the clock before you start the tour. Which is a great tour, by the way.

Edit -- The previous poster mentioned taking a water taxi from VCE into Venice. That would be fast and convenient, though very expensive. There's also regular bus service from VCE to Piazzale Roma, then vaporetto to a stop that's hopefully close to the hotel. Your call, but I'd go for the bus and buy that vaporetto pass instead of spending all that money on a taxi.

The water taxi from the airport is expensive, €140. After a transatlantic flight and an evening arrival I consider this money well spent.

What does your tour include? There is probably plenty to see in Venice outside your tour, but not knowing your interests or what it includes, it is hard to provide advice.

My vote is to stay in the city for those 3 days, personally. If you want to stay near the airport the first night, that is perfectly fine. But if it were me, I'd push through and arrive in the city. Your flight arriving at 18:00 may not mean you will have any time to see anything your first night but you can get into the city, check into your hotel and enjoy a nice meal somewhere.

Wake up the next morning and start the day fresh in what I consider to be the most magical city in the world. Get an early start if you can, before day trippers arrive. Get out in the sun and allow the Vitamin D help your jet lag. I went to Murano and Burano my first full day in Venice to assist with the jet lag recovery. If your tour does not include those, maybe that is an idea.

If possible, stay at the same hotel the tour will use. That will eliminate the hassle of and time lost relocating. Even if you can't get into the same hotel, do stay in Venice -- it's wonderful in the early morning and late evening when the day trippers are not present. If the tour does not go to Murano and Burano, that would make a good day trip that should consume about 3/4 of a day. Water taxis are expensive. Just take the bus to P. Roma and the vaporette from there. Can give details once you settle on a hotel.

Thank you all for your great advice!

I just booked a hotel near the Hotel Ala. NOT near the airport--thanks for saving me. The Ala did not have any availability for the days proceeding our tour. Thank you for the advice about checking for cruse ship arrivals. It would be great to explore another island on a day when Venice is crowded. Also, thank you, Dick for the list of activities that you did during your 3-day prior to tour. We will add some of those to our plans.

My next task is to find out how to get from the airport to the hotel. Hopefully, we will not be flight-delayed and traveling in the dark.

Thanks again,
Vicki

Getting to Venice from Marco Polo Airport. [Make sure you have seats on the right/starboard side of the aircraft, for a view of Venice as you fly into Marco Polo.]

Do take a look at your hotel website – there may be info there. Otherwise,

1. Water taxi will get you close, maybe to, the door of your hotel. Can carry about ten people, will cost about €140 for the boat. No need to book, taxis are waiting at the Marco Polo dock.
2. Shared water taxi. Minimum of two people. Book in advance, wait at the desk in the terminal for the others sharing the taxi. Costs about €30 per person. Google “shared water taxi Venice”, use the venicelink dot com web site. Will get you to a vaporetto stop near your hotel.
3. Alilaguna ferry, as per below.
4. Bus to Piazale Roma, then walk to your hotel, or take vaporetto to the nearest stop. Buses leave from the outside the terminal, tickets at the machine.

Water transport in Venice.
1. Gondolas. Only for pleasure, not for transport. 90 euro for half an hour for the boat, more for evenings.
2. Traghetto – big gondolas, two oarsmen, about ten passengers, for crossing the Grand Canal. Found at Rialto, San Toma and a couple of other places. Cost 2 euro per trip, can save a heap of walking.
3. Water taxis, which are like a floating limo, costs to match.
4. Vaporettos - ACTV. Are like a floating bus, operate on a bunch of routes. Get the app Chebateo for routes and schedules. Vaps do not service the airport. Vaps are not water taxis.
5. Alilaguna ferries, service the airport, run from Marco Polo via a bunch of stops to the main part of Venice, Murano and Lido. They stop at some, but by no means all, vaporetto stops.

If you want a break from Venice day trip by train to Padua or Vicenza

https://www.alilaguna.it/en/lines/linea-arancio
This line takes you easily to Hotel Ala so if your hotel is close, this would be a good option. We never took a taxi in Venice, though it did look like fun. This boat ride was also fun so it worked for us. The directions came from the Hotel Ala website.
Glad you decided against staying near the airport!