There are so many, and I may have used most of them! A couple that come to mind as being different than normal. The privy at the shelter just south of High Point Sate Park in NJ is the fanciest hands down. A giant heavy duty porta potty type design with a real door handle and even a solar panel on the roof (not sure what for though). There was a shelter in VT that had a 'famous' gazebo privy which had been relocated from a shelter that is now on private land and no longer an official AT shelter. All sides were identical. I would say Eckersville, but when I stayed the privy was locked for the winter. I hear it flushes though...