In such a place as Venice, the things a tourist must do (seeing places, buying things, watching festivals, etc.) might run into the hundreds. Unless you are staying for week (which could still be a short period for some people), you risk running out of days to explore most of Venice.
If your stay is limited for, say about three days, prioritize them down in a descending order. This is important because the tourism office might give you a list of “must-see” places. Do not engage for expensive tour packages just to do all those in your list.
If you’re only visiting and you only have a day or hours to spare, walk around the city streets first before going inside any church, building, or museum. This is a guaranteed way of discovering the quaint charms of the squares and city streets not mentioned in any guide.
Getting lost in Canareggio or Dorsoduro districts are perfect balms for your tired eyes. And then you can go and visit your listed churches and destinations. (Scuola di San Rocco church has some wonderful art masterpieces of Titian and Tintorretto.)
If you are lucky and still have a night to spare, then get lost in Piazza San Marco, just beside the basilica. The magic is mostly there in the early mornings and late evenings before the day crowds arrive or after they have left.
St. Mark’s Basilica
The all-time favorite of most people, St. Mark’s has its own distinctive beauty accented by its onion domes, multi-colored marble pillars, and the fascinating floor-to-ceiling mosaics. Although getting inside the basilica is free, the three museums inside have entry fees to get in.
Just beside the basilica is the Doge’s Palace, arguably the second most important attraction in Venice. One probable good reason to pay the hefty fee is the chance to walk across the famous Bridge of Sighs. (You can see the bridge from the outside, though.)
Taking the Grand Canal tour via the #1 Vaporetto, the water-buses of Venice, is equivalent to a city bus tour. It is slow, and it runs the length of the Grand Canal. Enjoy the sights along the way. (You may bring with you some take-along tour guide and some gelato.) Gondolas may be romantic but they are terribly expensive.
Even if you have not seen actual glass-blowing, you need not go with the demonstrations arranged by some packaged tours. Simply catch a vaporetto (not booked by your hotel) to Murano and walk around the streets until you find some open glass-blowing studio and watch the process without the large crowd.
The streets of Burano / Rialto market
Going for a stroll is great in the streets of Burano with its brightly-colored buildings. It is less crowded, and perfect for taking in the view. Check out, too, the Rialto market and see where the locals get their food. One note: if you like something, point at it and the vendor will pick and bag it for you.
Doing the things you want to do in Venice is not that difficult, if you stay away from the crowd and those tourist-filled destinations. Better still, try to visit during off-season. The prices are a little lower and the crowd is manageable.