Best way to get from Venice train station to my hotel

$50-$60 per person for private boat transfers

Huh?? A water taxi should be about 110 EUR plus a surcharge for the 5th, 6th & 7th person of 10 EUR pp. That is about 20 EUR per person, or $25 US at current exchange.
Here is the booking site. https://www.motoscafivenezia.it/eng/

There is also a surcharge for very early or late transfers, but never close to $50 pp.

According to Google maps, it is a 7 minute walk from the Venice train station, with fairly direct routes over two bridges. Not too bad, but I am sure a vaporetto (water taxi) would be glad to take you there.

Walk, and let the stronger people carry the luggage. I'm sure I've walked further to my apartment in Venice than you will have to walk. People manage with big suitcases across those Venice bridges all the time.

Oops, thought you were at the airport. Yes, a short walk over a couple of bridges, although one is a rather high bridge with a lot of low steps (Ponte della Constituzione). Or over the Ponte degli Scalzi, shorter with bigger steps. Or you could get a water taxi for 107 EUR per the previous website. Now we are at equivalent $20 per person.

Edit - a modest proposal, since it is such a short trip, ask the driver how much to ride you down the Grand Canal to San Marco and around the back way for 25 EUR a person. If you are going to pay that kind of money, get something out of it.

Use the link Sam gave you to get an actual cost--you can enter time of day, number people, number of suitcases, it will do all the calculation for you. And, yes, it will be much less than $50-$60 per person, and, yes, some water taxi pilot is going to be very happy--that will be about the shortest possible taxi ride.

It’s a 5 min walk from the station.
Is the boater quoting you those prices taking you to Croatia and Greece for a ride first?
Good Lord!

From the station to the hotel is two bridges. The Calatrava bridge is pretty easy as the steps are not so high, and the second bridge has ramps fitted for wheeled luggage.

Or, if you are getting vaporetto passes anyway, just hop a number 1 for the three minute ride between Ferrovia (the name for the vaporetto stop at the train station) one stop just across the Grand Canal to Piazzale Roma from which the walk is even closer.

That hotel used to be a Sofitel, by the way.

Sofitel is another range in the Accor galaxy, like MGallery.

Whoever quoted you $50-$60 pp for a 5 minute ride must be getting a big kickback. Hotel concierge, by any chance? Does that include the expected large American tip? I'm in the wrong business....

As you walk through the train station and your jaw drops as you see the view from the top of the stairs, keep to the right and you will find a ramp built into the right side of the stairs which will save you humping suitcases down the stairs.

Free advice - if you "don't want to carry heavy luggage too far", don't have such heavy luggage. There are lots of threads here in the Packing Forum, in the archives, and in links to pages written by Rick Steves here that can help you lose a lot of that weight - if you want to. Trust me though - for every pound you leave at home you will be saying, "Thank you Nigel".

A vaporetto is not a water taxi - It is a water bus, with fixed routes, rates and times.