Venice. What tours should I pre-book 7 Dec.-10 Dec.?

I don't think it's necessary to book advance tours in Venice except in the busiest seasons, or if it's a specialty tour. You can see the inside of the Bridge of Sighs with the regular Doges Palace entry. I think the best static view of Venice is from across the Grand Canal in front of S. Giorgio Maggiore ( or better yet, from the top of its tower.). The best moving view is from a vaporetto (or other boat) moving slowly from one end of the Grand Canal to the other.

I think this is the tour you are talking about. It does require reservations but I don't know how far in advance you have to reserve.

You should definitely reserve places for the Secret Itineraries Tour (loved it). There are only 2-3 tours a day and the groups are small, about 10-15 places only, so they often sell out. I also recommend these free walking tours. You need to sign up in advance to make sure you get a place, but you can do it a couple days in advance. There's no penalty for no-shows. I also like the view from the Campanile in San Marco. When you visit the Basilica, see the museum as well. It allows you close up views of some of the stunning mosaics and access to the balcony with its views of the piazza.

We booked a timed entry to the Basilica for a few euros- got us in first thing without a wait- not sure you would need in Dec.
Also booked the Secret Itineraries tour- which I highly recommend. When it ends you are free to tour the Doges Palace on our own.

The view from San Marco Campanile is fantastic- try to do it just before sunset

I took a tour of the cathedral and Doge’s palace with Walks of Italy which was very good. They have a sale on thru Nov. 30 - 30% off.

Thank you. Booked the Secret Itinerary tour. I've read about a Vivaldi concert that takes place in a church that Vivaldi would frequent. Trying to find information on that. Also, can we purchase tickets to San Marco Campanile in advance or there won't be a need to in December?

Here's a link to the church you're asking about. You might also want to look into Interpreti Veneziani...I've seen them 3 times, always entertaining.

You will probably end up walking around the Campanile several times. Just keep an eye on the line. There's limited access - the elevator is small and there isn't all that much room in the belfry, so the line may be at the entrance, not necessarily for tickets.