I have been to a few parties in my time, but dancing in a tree house is something I haven't done.
In the past year there's been a series of parties in New Orleans in a big tree house in the grounds of the NOLA Art House, an old Creole mansion (built c.1870) where loads of artists live and work. The tree house is a 5 storey structure, apparently including a pool (not sure if that's up the tree or on the ground nearby).
The place looks amazing. According to one party goer: 'For anyone who's been in the tree house, the fact that anything at all is keeping it up is only slightly reassuring. When the installation is full of people dancing to music spun by DJs, the whole structure reverberates with the beat. The shaking is not so fun when you're standing on an isolated pod and the only person who can help you off is busy taking pictures of your terrified face'.
Lot's more about it here. They are having a Mardi Gras Festival of the Rising Sun in February - prompted by the story that the The House is said in several guidebooks to be the original House of the Rising Sun. Sadly I'm in New Cross rather than New Orleans, but if you're in the area check it out.