Moon is one of the better clubs in Vegas I think. My girlfriend and I came on a Sunday night around 12AM. Although there was a line, the bouncer told my friend and I to go directly up to the rope where they were letting people in. When we went up to the rope, another bouncer asked us if we had a reservation or if were on guestlist. After telling him no, he let us in right away anyways.
The cool thing about Moon is that it's up past the 52nd floor. So from the outdoor patio/smoking area of the Moon, there is an amazing view of the Strip. As for the club itself, it isn't very big, but the atmosphere is pretty chill. I feel like they have a good sense of how many people to let into the club. The Moon is small, but there was a good amount of people in there. There's enough people in there to have fun and not have the place feel empty, but little enough people so you can still dance (not ridiculously packed like at Tao for instance).
The club is pretty cool looking and if you pay cover for the moon, you have access to Rain, Ghostbar, and the Playboy Club. Yeah, the drinks are kinda expensive, but hey, you're in Vegas, and they don't skimp on your alcohol here.
Definitely a fun club. Music can be good, but also kinda sucky. Music sucked in the beginning, but got better towards the end of the night. Also surprisingly, bouncers are pretty friendly here.
If looking for a fun club, I would reccommend the Moon as one of your options.