You have a few options. You can take the bus or a taxi from the airport to Piazzale Roma and then hop on the Vaporetto and get off at the Ca’D’oro stop. Hotel Al Vagon is just a few minutes walk from the terminal. Another option is to take the Alilaguna Water Bus directly from the airport and get off at the Rialto stop. Your hotel is actually about midway between the Ca’D’oro stop and the Rialto stop, so it’s just a few minutes from either terminal. You will want the Alilaguna Orange Line. The advantage of the Alilaguna service is that you don’t have to transfer from a bus or taxi to the Vaporetto. These options should both be available to you during the day or at night. There is one last option, which I sometimes hesitate to mention as it is the most expensive option. This would be to take a private water taxi. Expect to pay at least 100 euros for this option. If it’s a nice day or evening the ride through the lagoon can be pleasant so certainly take into consideration the weather when deciding.