I vote the classy look. Especially if she is going out to a party... I think the way a person dresses, especially in the "dating scene", will determine what type of person she will "pick up" and perhaps their intentions as well. Of course, thats not 100% accurate, but I'd prefer wearing something sexy but classy at the same time. It's a representation of who I am, what I am about.. First impressions are important and IMO, if I were to wear a mini skirt showing off my cha-cha, most men probably would want to have sex, but that's about it.
I dunno, maybe I am completely wrong, but if I were going out into the dating scene (which I am not because I am with someone), I would try to leave a bit of mystery rather than reveal it all for the world to see.