I don't know where you'll be coming from, but generally I'll say that the motor launch (boat) from outside the MK is the way to go. The boat is outside the main gates (the same way the monorail and the buses are outside the main gates) so you won't need MK admission. This boat will go from MK to Wilderness Lodge and then to Fort Wilderness. When you get off the boat at Fort Wilderness, there is only one road/path, and Pioneer Hall is right on that path, a VERY short walk by WDW standards.
By contrast, if you take the bus to Fort Wilderness, you will then have to take a Fort Wilderness internal shuttle bus to get back to Pioneer Hall, or else face a LONG walk.
The boat was fun both ways, if taking boats is a unique experience for you. And here's a bit of well-known trivia. At one point, the BOAT goes over a bridge, and that bridge is over a road! They built an artificial connection between two lakes (both of which are probably artificial, too!), and that connection is a bridge. When you take a bus to MK, just before making the left turn into the MK bus complex, the road dips down and goes under an overpass and then the road rises up again; that overpass is part of the lake!!! Neat thing to point out to kids when you're on the boat -- it's a pretty unique experience to ride in a boat that is sailing OVER a street!