From the airport you have a few options. You can take a bus or taxi to Piazzale Roma and then take the Vaporetto, Line 1or 2, and get off at the San Marco stop. Your hotel is a short 10 minute walk from the Vaporetto terminal. Another option is to take the Alilaguna water bus directly from the airport to the San Marco stop. You will want the Orange Line. You can also take a private water taxi directly from the airport. They will get you as close as possible to your hotel, which makes this the most direct and quickest choice. This option is clearly the most expensive and will run you at least 100 euro.
One word of caution with regard to luggage. Venice is not luggage friendly and getting four bags around in Venice can prove challenging. The best option for getting from the airport into Venice depends on how much you are willing to spend and how quick and easy you want the trip to be. The easiest and quickest option is also the most expensive. The bus/taxi option followed by the Vaporetto requires a transfer from vehicle to boat, and then walking to your hotel. The Alilaguna option is just one boat trip followed by walking. If money is not an issue then the private water taxi would be my choice. If the weather is nice then the Alilaguna option would provide a nice ride through the lagoon out to Venice.