In early December 2023 we visited all three places, San Giorgio Maggiore, Torcello, and Burano, and thoroughly enjoyed all of them. Torcello was a huge favorite for all six of us, including two young kids.
There is great art in San Giorgio Maggiore, but without being able to go up in the belltower I'd be inclined to save it for a future trip. Burano is very cute with all the houses in different bright colors --- this was my husband's and my 2nd visit to Burano and we were a bit shocked at how heavily touristed it was in December.
Here's what we loved so much about Torcello. We went early in the morning in order to get to the church when it opened at 10:00am. We took the vaporetto straight there and the ride over the lagoon was a joy in itself and a nice contrast to being in the city. We enjoyed the walk along a canal to the church, seeing fields and flowers and one of the two remaining bridges without railings. Yes, you can walk across it. We had the path, the bridge, the church, and the tower all to ourselves, only running into other people when we left to go back to the vaporetto stop, and even then it was only a small tour group. I'm assuming there would be more visitors in October, but I bet nothing like the crowds in other spots.
The views from the tower are of farmland and water, so not as exciting as the views from San Giorgio Maggiore of San Marco and the city, but still lovely and interesting. The steps in the tower are unusual, being interspersed with short ramps, and the two of us with foot and ankle problems found them to be much easier than regular stairs.
Right, no photos allowed inside the church, but there are online photos and youtube videos --- here's an educational one about the history and restoration of t:he church and showing details of the mosaics Torcello church
We had lunch on Burano on the way back, but you could just return to Venice for your sauntering and soaking for the rest of the day.