Technically the Wilderness lodge is the smallest footprint and it is all in 1 building. It has ~340 rooms over 7 floors. It's capacity was reduced from 728 rooms when the south half was converted to the Cooper Creek Villas.
POFQ is the smallest footprint, but if you're looking for a deluxe resort, the Boardwalk and Yacht and Beach are all fairly small and contained. Those three are also so close to EP and HS that overall walking may be reduced a bit.