There is a ferry that will yake you. It let's you out on the West Side.
Depending where your room is...it might be quicker to walk. we stayed in the "Paddock" area. There is a nice walkway from that Paddock pool area that takes about 8-10 minutes to get to the closest part of the Marketplace area. It's actually anice walk !!
Buses are always an option.
Good luck
It depends on where in SSR you end up. There are three ways, walk/bus/ferry.
If you are in Congress Park it is fastest to walk. Most other areas it is generally quickest if you take the ferry (for Marketplace). If you are going to West Side, there is a different path there up near the Carriage House/Grandstand Area.
All of this is also based on how fast and how much you enjoy walking.
Keep in mind the walkway that takes you to the entrance near WPC and the Christmas Store, The art of Disney etc. closes at dusk. I recommend you take the boat back if coming back at nighttime. We made the mistake of walking back at night and it was freaky lol.