It really does depend on the time of year that you visit. Summers, Spring Break, and Christmas are going to bring crowds. January, early February, and early Autumn will be less crowded.
That said, the WL pool always seems to be pretty full. The WLV pool - Hidden Springs - is an option, and it's often less crowded than the main pool; but some folks want to reserve that solely for DVC members -- you have to wrestle with your conscience on that one. The sign specifically says "for guests of Wilderness Lodge" or some such.
When are you planning to go to the Lodge? Would love to hear about your trip!
WildernessLodgeSite.com
An unofficial tribute to Disney's Wilderness Lodge and Villas