I have technically slept in the Swiss Family Treehouse. I had worked until 2:45 (extra magic hours), and had to work again in the morning (I think around 9). I had planned on just sleeping somewhere in the utilidors, or perhaps even in our break room.
However, a cast member I knew recommended sleeping in the master bedroom of the treehouse, as he had actually slept there the night before Hurricane Charley hit in 2004 (it was just raining, no heavy winds yet!).
At 3 ish I just walked around the park (I was still in full costume, so It's not like I was standing out, considering there are many cast members in the park overnight). I took some pictures around the park (always fun to take some pictures when the park is essentially empty), walked around a bit more, then headed back to the treehouse around 4. Slept from about 4 til 6.
Headed down to the utilidors to get some breakfast in the Mouseketeria, then went back to my breakroom to sleep for a couple more hours til it was time to work.