Gianni's place is a really great apartment to use as a home base to explore Venice, or even to self cater because the kitchen is open plan and looks out on a canal with floor to ceiling windows that are also doors to a balcony.
Location-wise, it's super central, and close to most of the things that are probably on your list. It's also far enough away from the busy roads and canals to make it very quiet.
The check-in is from a nearby hotel, which also has a second floor with an incredible view. Gianni recommended it, and I would too. The service, food, and drinks were great.
I can't recommend this highly enough.