The cheapest and quickest way to get into Venice is to pick up a 72 hr bus and Vaporetto pass at Marco Polo airport and catch the bus (remembering to get your ticket stamped in the machine by the bus stop) to Piazzale Roma where you can get the Vaporetto down the G Canal to your hotel. This ticket is about 25 euros but you can use it for 3 days on any bus or boat and back to the airport if appropriate.
Alternatively you can get the Aliguna waterbus which is slower and more expensive to St Marks if you want to arrive by water.
If you can possibly afford it get a water taxi right to your hotel from the airport for the most stylish way to arrive - 85 euros now I think but will take 4/5 people for that price which makes it a bit easier on the wallet. Its the most wonderful way to arrive, I felt like a cross between Audrey Hepburn and a princess!
This post has not been commented yet.