You can take a bus to MGM and walk (about 10-15 minutes) or take the Friendship boat to the Boardwalk. You can go to Epcot (via bus or via boat then monorail) and walk through Epcot and out the IG where you can walk (5 minutes) or take the Friendship boat to the Boardwalk. The Epcot option requires a park ticket. Outside of park hours, you would have to go via DTD.