There's also the classic "party" trance: Darude, either of his CD's ("Before the Storm" or "Rush"). Also, "Trance_Fixed", "Trance_Fixed v2.0", "Trance Stimuli", or "Trance Stimuli Version 2.0". Those are my favorites for trance CD's.
A lot of people also like stuff by Paul Oakenfold, DJ Tiesto, or John Digweed.
Another suggestion: Do you have iTunes at all? Or does she? (Wherever the party is going to be, I guess). Or go to www.di.fm if there's no iTunes. The reason I suggest this, is that you could play internet radio for the night, so there'd be no bother with CD's. There's multiple types of electronica available through the di.fm website, so if there's a music player on a computer, hooked up to a stereo system, you could play any of those streaming stations and be set for the night!
I also just realized that I downloaded 2 CD's: "iTrance 1" and "iTrance 2" and they're pretty good (to me anyways! ). They are only available through the iTunes Music Store though, unless someone has it shared somewhere else...
if you like disco music at all, "dmitri from paris a night at the playboy mansion" is very fun. he remixes disco songs that are off the beaten path, so you'll probably hear a lot of stuff you haven't heard before.