re: Falling Water
I would love to see that place in person. It's a masterpiece, although Wright has often had some problems with the technical/engineering side, and Fallingwater was no exception. I think they just recently finished upgrading the structure, which was sagging.
I'm in Northern California, and would be nervous about building my house over a mountain stream here, but maybe the streams in Pennsylvania are not quite as Jekyll/Hyde as the ones here.