"Only a stone’s throw from Saint Mark’s square" is the standard hotel claim. Whether or not that’s the case, it’s not necessarily an advantage. In Venice, you can't go terribly wrong in terms of "good" areas in which to stay, and once you get your bearings, you’ll find you’re never far from anything.
The area in and around San Marco will always be the most crowded and touristy and almost always more expensive: even two- and three-star hotels cost more here than they do in other parts of town. If you want to stay in less trafficked surroundings, consider still convenient but more tranquil locations in Dorsoduro, Santa Croce, and east Cannaregio (though hotels near the train station in Cannaregio can have their own crowd issues), or even Castello in the area beyond the Pietà church. A stay on the Lido in shoulder season offers serenity and beaches for the kids, but it also includes about a half-hour boat ride to the historic center, and in summer it’s crowded with beachgoers.