We’ve stayed in the San Polo sestiere twice and in the Accademia area once. All three visits have been during quite warm weather and Venice has never been smelly. I find the only humidity problems on any of our travels in Italy to be when we stay in old stone buildings on a lower floor-they can be a bit damp and musty. Our last stay did have a canal and campo view and the stay was neither humid nor smelly.
Since you are there for only 2 nights, the San Marco accommodation might be nicer from the standpoint of location but since you don’t think you will visit the Basilica, then San Polo is better especially since you want to walk to and from the station.
As for Burano and Giudecca, I’m not sure either preempts just wandering Venice. Burano is colorful and interesting-lot lots of tourists. Giudecca has views back to the main islands of Venice, but other than San Giorgio, which is a separate island actually, and the Redentore, there isn’t that much of interest there unless you happen to be there on the day that the women’s prison has their garden market. It is a different feeling to wander around over there, but the best part of being in Venice for us is trying to find ways around that aren’t very crowded. Granted, not always possible but there are places. In fact, this past May when I stayed by the Accademia, I wandered around the entire area behind my hotel and onto the back side (Bacino) of the area and found all sorts of interesting buildings and sights and hardly any people. Not necessarily the grand views and buildings of Venice, but picturesque and great views of the Redentore and Giudecca.
I didn’t visit the Basilica di Santa Maria Gloriosa dei Frari until this last May and I found it to be one of the most fascinating Basilicas I’ve been in mainly because of the monuments for Casanova, the sculptor, and Titian, the painter. St. Marks is a wow of it’s own, but the Frari was a joy. However, even if you don’t feel you’ll be interested in St. Marks, it is really rather magnificent. I am not religious but have found out I like going into every church, Basilica, chapel, etc because they are so very different from one another. The fixtures, the floors, the columns and the capitols on the columns, walls, pews, tile work and hand painted illustrative work (not paintings or frescoes)- ceilings can be fascinating. There are magnificent features in these buildings besides the famous religious paintings and sculptures that are exquisite at least to me. I have a BFA in art and can easily pass on every single painting in the churches!
Buy a 2 day vaporetto pass and just ride those around. You can see so much, easy off, easy on. They take you everywhere, albeit not quickly-stand outside or try for the ends of the vaporetto that has seats. Sitting inside won’t give you the views. The app Che Bateo is fabulous. IF you do this, please remember to validate EVERY time you get on a different vaporetto even if you get off and get back on at the same place.
You can eat inexpensively in Venice if you look around. Off the main drags are certainly better and more interesting. Most pasta dishes are €12-13 each and plenty to eat. Cichetti for dinner. I like them but tire a bit of all the bread with them. Aperitivos always have snacks, anywhere from simple potato chips to more items. Pizzas are large and generally very good and range around €12-15 each. Breakfast-if you can handle the traditional Italian breakfast of a coffee and sweet such as a croissant - cornetto- then €3 is the max you should pay for that. Get a good paper map-not google as it often doesn’t work well- go off course. There are hundreds of eateries in Venice. I would advise if on your wanders you see a place you might like to have dinner, try to make a reservation right then for evening. Sometimes though it can be a matter of asking for later in the evening if you arrive without a reservation and they say they are full.
As you can tell, I love Venice. Enjoy.
