Why not spend time warming her up BEFORE the party and concentrate on keeping her on her toes all evening rather than trying to do it AT the party.
Public sex is good and all until you get caught by the police. Just keep that in mind. You're missing the basic question of what HER fantasies are, and what would turn HER on. Not what would get your engine purring.
So, find a way to get her really worked up before the party, then slip in some alcohol and a lot of intimate touching when you're close. I could give you a lot of ideas, but seriously I'd have to know a lot more about the woman to help you here.
One that I've mentioned on this site before is to get some paint brushes and learn to whip up a quick warm (not hot) chocolate fondue and paint her with them. The quicker route being to just buy chocolate body paints and warm them up a bit, but sometimes effort counts.
I mean, you could get a vibrating egg w/ a wireless remote, slip the egg in her, and have fun flipping it on/off at the party while she's in public view. The batteries get a bit expensive though as they use like 6 or 8 watch batteries fyi.
Pretty much if you want HER to really enjoy it, then the focus needs to be entirely on meeting HER needs in bed, not yours. You're a guy. You need a wet hole and some thrusting to get off. Most women need a lot more than that. Hell send her to the party after 2 orgasms w/out sticking your cock in her.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."