I have a number of photos taken over a few years of the best "loos with a view" but my all time favourite is the one at the refuge in the White Mountains in Crete which is just a wooden seat with a hole cantilevered several hundred feet over a (fortunately inaccessible) gorge.
A close runner-up is the ladies on the paddle steamer "Waverley" which is situated above one of the paddles. Talk about the shit hitting the fan!