I've had hands down my best luck at parties where lots of the guys there are gay. Last night (on a sunday, i didn't even think that was possible), I went to a party hosted by a couple of my fraternity brothers, who are gay. Small affair, but they have some smoking hot girl friends, and even though there were more guys than girls, only one other guy and I were the only straight guys. Do the math, it worked out real well. Additionally, gay guys are known for throwing very enjoyable parties, and they soften up the girls for you (lots of upbeat chit chat, and they're always playfully grabbing each other, which gets the girls wanting the real thing).

TL;DR - go party with gay guys, plenty of hot women there, and the guys won't steal the women.

Edit: Hook-up last night also works at the JC Penny by my house. 20% discount FTFW