venice for two days

You can pick up a route map at the booths that sell tickets. Think of it like a bus system, and approach it that way. I always get a vaporetto pass for the number of days I'll be there. Even though much of Venice is walkable, it's nice to be able to hop on/off whenever I want. Lets me save the walking for the sites. I also enjoy 'joy riding' on the vaporetti. The single ride tickets are quite expensive; don't know how much since i've never bought one, but it makes the passes a good buy.

It's unlikely you'll want visit enough of the sites covered by the Venice Card to make it pay. A vaporetto pass will. A 48 hour pass is E35 while a single trip is E7. The ability to hop on and hop makes it worthwhile.

You can get the transport passes at www.veniceconnected.com. The 48 hr pass is 30 euro. If you are arriving by air, you can add either one way or return bus to the airport for 4 and 8 euro respectively. You can also get the museum passes at this site, one visit to all museums or just the ones in St Marks.
You can download the vaporetto map and get timetables at: http://www.actv.it/en/movinginvenice/waterbusservicestimetable

Thank you for all your help. :)