Boutique San Marco is an incredibly charming place right in the heart of Venice. If you follow the directions it's pretty easy to find (it's really only about an hour walk from the bus station to the hostel so you don't really need a water bus pass, just walk to Piazza San Marco and work from there), and once you're there everybody is super friendly and helpful. You'll probably be sharing a large room with a number of other people, so be aware that it is a very social place. Overall we had an amazing time on our trip to Venice and it was due in a huge part to the excellent accommodations and service we got.