I can't recommend Loredana's flat highly enough.
We found it to be spotlessly clean and well equipped, in a delightfully quiet location (while being only minutes away from both San Marco and the Arsenale), and extremely easy to find from public transport (plus a one minute walk from the closest supermarket).
Loredana was great to communicate with - everything went smoothly, from booking to key handover.
Will definitely be coming back!