Our trip is just a month away and we are working on the details. We will be arriving in Venice on a Friday and leaving Monday morning. Could anyone tell me what is open on Sunday or if most things are closed. Also, would Sunday be a good day to visit Murano and Burano?
Sunday is a good day. According to Rick Steves' Venice guide, "all the recommended sights are open" Thursday through Sunday. Do check the hours of museums you wish to see, though, since you will still be in off-season. Do you have the Venice guide? Essential, IMO, for the details! Have fun! Venice is a magical place.
In general, most attractions are open or available on Sundays. Venice is great because most of what you want to see is just the city itself. Murano and Burano will be great to see on a Sunday. If there is a specific museum you'd like to know about, go to the Venice Tourism website at: http://www.turismovenezia.it/eng/dynalay.asp?PAGINA=1399
Since you're really going to be there for only two days, I would recommend against going to Murano and Burano. They're fine, but definitely lower priority IMHO to seeing more of Venice proper.