Im with complawyer, I like booking my own flights. It cost more but at least you know that you won't be taking 3 flights or 38 hrs to get to your destination.
Venice is a nice city to visit, If you stay there a couple of days do your research on hotels, lot of stairs from island to island, it can be a pain going up and down stairs with luggage. We stood walking distance to main train station and in front of the station there was a bus that took us strait to the airport (VCE). Also the gondola ride on the grand canal is a must, just get your bubbly ahead of time, Enjoy!