Came for Dirty South last weekend when my friends were in town. The venue has 3 stories: Main room (for the headliner DJ), house room, and hip-hop room. I only stayed in the main level the whole night. In fact, my friends got a cabana for us to hang out in outside the main room.
Pros: decent music from the headliner. awesome large, exterior patio.
Cons: crappy mashup hip-hop house music before the headliner. the bathroom was a pain in the ass to get to from the outside. the main dance floor could be bigger IMO.
Tip: If you know you want to go to Marquee, just buy pre-sale tickets a few days ahead, and there is virtually no line at around 9-10 pm. If you do purchase pre-sale tickets, get your actual ticket on the first floor of the casino, jump in line on the third level (past the pizzeria), get yourself stamped, and then go back to your room to liquor yourself up and enter any time you want.