Venice

Piazzale Roma is a fairly large square, that serves as a terminal for the bus services to and from Marco Polo and Treviso airports and other cities. It is the main entrance of tourists in Venice and not the prettiest picture to see when you first arrive in Venice. 

Around the square there are parking garages, since Venice is a completely car-free island.

There are two buses from Marco Polo airport to Piazzale Roma:

ATVO (Azienda Transporti Veneto Orientale, www.atvo.it ) via Mestre (20 minutes and 3 euro)
 

ACTV (Azienta Consorzio Transporti Veneziano, www.actv.it ) with more stops (30 minutes and 1 euro).
 

There are many nice and relatively cheap hotels near Piazzale Roma. The advantage to book a hotel near Piazzale Roma is that you are very near either the bus station or the train station (Ferrovia). This makes very easy to carry your baggages, if you have many. Piazzale Roma is very close to all the attractions of Venice and it doesn't take longer that 30-40 minutes to reach by foot San Marco square. But you can easily use the vaporetto.