Marco's place is a gem. It's seated in an area far from the tourist spots which makes it a very relaxing spot. Far but still very walkable. The area is also in a student area so expect affordable restaurants nearby. The place is also great for big groups or families. Only red flag here is that the flat is on the third floor, and since the bldg (like most bldgs in Venice) is old then it cant house an elevator anymore. Be careful or be ready if you are carrying heavy luggage.
Monica is also a great person, she will help you by providing tips for whatever you want to do.
Would recommend this place, would book if I visit Venice again.