Marco's place is great. We had a great stay in Venice, partly due to the great accommodation he has. The place was clean. The beds were comfortable and there was enough space for the five of us. The apartment has everything needed for a family to feel comfortable. We really felt at home. One big positive aspect is the location of the supermarket so close to the house. It's literarily about 30 seconds on foot and opens every day (including Sundays) non-stop from around 8:30 to 20:30 (this may vary slightly depending on the day of the week).
The place is also close to San Marco's square and to the waterbus station San Zaccaria. There is a direct line from Santa Lucia rail station to San Zaccaria, so if you're arriving by train, it's very easy and practical to get to the house.
It's also even closer to the north side of Venice where you can take the boat from Celestia station to Murano island and then to Burano.
There is a locker in the building hallway where you can store your luggage, in the event that you need to check out but still have some time for a last stroll before heading back to the train station or the airport. It's quite practical.
We will definitely choose Marco's place the next time we are in Venice.