Just pick a person with the same taste in music as you. I have never met anyone who liked the same music as me the I didn't become super good friends with. Seriously, you can learn a person's entire personality by they're musical tastes.
But I don't have a taste in music! (Unless anime openings count...)
And I'm more worried about the overall awkwardness if I take a guy I've never met, especially if I meet him the night of the dance. People at my school tend to be...showy when it comes to relationships, and we might stick out
But SFK you make a good point. I suck at meeting new people, so this could be a good opportunity for me. After all, its only Cotillion.