There are several option in order to reach Venice from Marco Polo and Treviso Airport: ACTV buses, ATVO fly buses, water taxi, Alilaguna boat.
The main transportation method in Venice is you...or better your feet.
Distances aren't so long and every place can be reached by walk, although its very easy to get lost if you try to venture off the well-marked central pedestrian routes.
But if you are tired, you have luggage or you simply want to cruise the canals you can take a Vaporetto, a Gondola or a Water taxi.
It depends only on how romantic you are and... how much you want to spend.
