Definitely buy the Venice pass in advance of your trip for unlimited access to the water bus that you will need. Get your transportation from the airport through Alilaguna (15 euros each one way). Takes an hour to Lido with no transfers and the public one at 6 euros each one way will take a little more than 2 hours.
The unit is very quiet and spacious. Go to the bar to the left 4 doors down for your coffee and fresh out of the oven croissants before you head back to Venice.