Using the awesomeness that is Microsoft's Live Search Maps, I calculated some walking distances around the resort. I was bored.
Disneyland entrance to most distant point (Splash Mountain entrance, also western end of Toon Town): .45 miles
DCA entrance to most distant point (TSMM, also Maliboomer): .4 miles
Disneyland entrance to DCA entrance: .06 miles
Downtown Disney Monorail station to DL or DCA entrance: .33 miles
DLH to DTD Monorail station: .1 miles
So that means the two most distant points in the resort (not including the parking structure) are Splash Mountain and Toy Story Midway Mania, a walking distance of .91 miles.
From the DLH to Splash Mountain is .89 miles.
Next time I go to Disneyland, I think I'm going to do laps: Splash Mountain, Toy Story Midway Mania, SM, TSMM, etc. - repeat until closing or I drop.
Anybody want to double check my math?