I was just at the WL, and there aren't any boats from the GF to the WL. There is a boat that goes from the WL to the contemporary and FW. And there is another boat that goes from the WL to MK and FW.
To get to the GF, you could take the boat from the WL to the contemporary, then go the 4th floor of the contemporary to take the monorail (I think 3 stops to the GF). I don't remember when that boat stops running- I think it was like 10:00 p.m. or so, cause we went to dinner at the contemporary a few nights and were never worried about the boat ride back since it ran late.