I had a chance to visit a tree house exhibit that The Berkshire Botanical Gardens (a beautiful place!) had last year, and I even shot a video on the structures that dotted their property. One "tree house", or more so a pole structure, that I felt was the best of the bunch was a cube-like, 8' by 8', lofted hut that was designed by Joseph Cho and Stephanie Lew.
A structure like this, as you'll see in the the video excerpt, could be used, or morphed into a great little vacation, or getaway cabin, especially as one that would be versatile on less savory land and terrain- after all, once its four poles are set, you're good to go. On a hill, or in flood prone or swampy areas, you would have no problem with a simple cabin like this.
This pole house, apparently, was inspired by Japanese-style lanterns, and while I wasn't there to witness it lit up at night from within, I'm sure its spectacular. You can find more on this duos work at www.binoculardesigns.com
Photos from www.berkshots.com....
-Derek "Deek" Diedricksen