Venice in June w 12 year old granddaughters

Just suggesting that you make sure that the hotel that you choose is quite close to a vaporetto stop (or water taxi stop, if you arrive that way). Guiding 12-year-olds and handling their luggage through a maze of small streets, up and over possibly multiple bridges, could be quite a hassle! Please look carefully at maps to assess where the hotels from which you can choose are in relation to a close vaporetto stop. You will also likely be using the vaporetto multiple times to get around Venice. Once you arrive, I suggest that you get vaporetto passes for each of you; multiple-day passes are available from the vaporetto office and ticket machines - all found on the dock outside of the train station and also when approaching the dock at Piazzale Roma (where you disembark from the bus from the airport). Also: having taken young teens to Venice at different times, all loved walking around Murano and watching glassblowers' demonstations (and then buying small glass animals to take home). Finally: You don't say when you might be traveling, but of course (as you are likely aware), vaccine and Covid-testing requirements for US citizens entering Italy are complex and often changing. Since your granddaughters are 12 years old, you may need to see that they have proof of vaccination. One very recent traveler to France and Italy just posted her experiences on this website, https://community.ricksteves.com/travel-forum/italy/just-back-from-france-and-italy, and other folks may have even more timely information.

I suggest you use the search feature for the forum, typing in Expedia. There have been problems with them and other 3rd parties if you need to change flights or hotels, have flights changed/cancelled, etc. You need to be aware of your risks if not booking direct with the airlines and hotels.

I only booked with Expedia domestically once years and years ago. I was not allowed to change my return flight and ended up buying a one-way ticket home.

I would also caution against buying airline tickets just now from anyone but the actual airline.
Since Covid appeared, it's difficult enough to get refunds from airlines, never mind third party sellers, in case of plans changing, Covid rules changing, etc.
Expedia was great in the past, and I've used them myself a few times over the years; but right now I think it's better to be as cautious as possible, no matter how good the "deal" is.
You don't want two disappointed 12 year olds to deal with!

Check and see what it would cost to book the same flights/hotels yourself and compare to Expedia package. I had a flight through them that was canceled when Covid hit. They refunded everything without difficulty and I would be willing to use them again for the right deal.

Here’s a trip report I did in 2019 on our trip that included Venice and a packing list requested by one granddaughter:

https://community.ricksteves.com/travel-forum/trip-reports/italy-and-paris-with-teenage-granddaughters

You have some very lucky granddaughters. I highly recommend:
1. taking a vaporetto (water bus) from one end of the Grand Canal to the other i.e., the train station and San Marco Square at dusk. This way you won’t see the decay on the palaces that line the canal and instead see the large crystal chandeliers that illuminate the palaces spacious foyers. The experience literally took me back in time.
2. The other one is to get lost. When you’re ready to get back on the beaten path, follow the crowd.

Visit https://europeforvisitors.com/venice/ for a good intro to hotels and transport.