There are 3 ways to get from the airport to your hotel. The 1st is a water taxi and they are quite expensive. Probably 125 Euros for a private one. I understand there is now a shared water taxi that will lower the cost, but I've not used them and do not know how much they cost. Perhaps others who have used them can comment.
The 2nd and next least expensive is the Alilaguna boat. It will cost about 20 Euros per person. It takes longer, you do have to "check" you baggage so you don't have control of it the entire time, and you probably will not be able to get a "non stop" line to the area of your hotel.
The 3rd and least expensive is a combination bus and vaporetto (vap.). It takes a bit longer, but that is what we do because we travel very light with just one carry on apiece. There are two bus lines that serve the airport. One is ATVO and is NOT affiliated with the vap. system. The other is ACTV and IS affiliated with the vap. system. At the airport you can get a vap. pass for various periods from 24 to 72 (or more?) hours. You can have a one way or two way bus fare added to the vap. pass. There is a good site maintained by the ACTV system that has current prices and etc.. Don't remember the url so just Google it.
If you decide on option # 3, take the # 5 ACTC bus from the airport to Piazzale Roma. Be sure and validate the vap. pass on the bus. Do not wait until you get on the vap. Also, validate the pass each time you use the vap. Then take to the vap. to the stop closest to your hotel. It appears the # 1 vap. is the one you should take to the S. Maria del Giglio stop but double check with the hotel. Then just walk from there .
The hotel can probably give walking instructions from the vap. stop. Or you can go to googlemaps.com. and type in the hotel name and address. You can get aerial views and street views and can "walk" the route before you leave home. We've done option # 3 many times. Easy Peasy and cheap to boot.
There is a site called veniceforvisitors.com that has a lot of good info. that you might want to check out.