This appartement is calm and beautiful, superbly distributed with 3 real rooms sitting at the right distance from the living room, a lunch room, and a near-professionnal kitchen.
Its situation on the map is strategic : 3' walk from the Rialto bridge, one of the most typical & nicest area in Venezia and 10' from the boat stop to the others islands (Murano, ...).
Dorssoduro & San Marco are definitely reachable by feet, with two childs (8 & 11) and their grand-parents ;-)
In short: Rialto's fish market + top class kitchen + easy walk to everywhere in (arguably) the most charming city in the world... Do not hesitate anymore: run to Marco's flat !