RumJungle was quite the experience...
Went with the fiance, so I kept the partying mellow. RumJungle happened to be the first place we encountered when entering Mandalay Bay. No cover and a super friendly (maybe Somoan?) bouncer. It was super dead and the party was just about to start. No one on the dance floor.
There was a lot of bench seating available around the two dancefloors. Thirty minutes and 3 drinks later, we started watching our bench neighbors getting down on the dance floor. It was a very interesting night because it was unlike any crowd I have ever seen... everyone looked like they were in their 40s and/or corporate nerds that never get laid. I probably wouldn't do a repeat, but I had fun.