I would say this is probably my second favorite. My first would be Wrights home and studio in Spring Green, Wisconsin.The house that is of the hill, Taliesin.

http://0.tqn.com/d/architecture/1/0/K/z/Taliesin.jpg

Fallingwater is a breathtaking beauty almost like a fashion model and just as high maintenance, shes just not a very practical home. It dosent even have a garage. Taliesin on the other hand is a self contained farm estate with drafting studios and workshops, Wright even built a dam and hydroelectric power a full ten years before any of his neibhors.