why don't you make it into a "guy-buy-girl-a-drink" party. Here how it works:
The rule of the party requires guy to buy a drink to any girl he is interested in. If the guy bumps into a girl of his interest, he can approach her and buy her a drink. The more drink the girl get, the more attractive she is. Of course, if you are a gay, you can also buy your guy friend a drink... only in this party.
The benifit? it is a easy ice-breaking tool in an party with many people from different places.
Hope you like the idea.
Have fun, guys and girls.