You can take the Alilaguna Water Service directly from the airport to the San Marco Terminal. Both the Orange Line and the Blue Line stop at San Marco. It's about a 45-minute ride followed by a short walk to Hotel Concordia. Or, you can take the bus or a taxi from the airport to Piazzale Roma followed by the Vaporetto to the San Marco Terminal. Piazzale Roma is the end of the road for land vehicles, from here it's either by foot or by boat. The Vaporetto Line 1 and 2 both stop at San Marco.
The cost is about the same for both options. There really is no quick way to do this as both methods will take upwards of an hour. If it's a nice day perhaps the ride across the lagoon with Ailiaguna would give a unique perspective as you approach Venice.