I caved and went in a dress. I remember telling my mother that I wanted to go in a suit (which I'd been mustering up the courage to say for months), and she gave me a look and said that it had to be very femininely tailored to look good. Whenever I brought it up again, she'd dismiss it, so eventually I just went with the dress that she picked out for me.
I ended up having as much fun as I could have, anyway*. And I looked good for a girl. It's the "for a girl" part that bothers me.
*(Although at one point I got sandwiched on the dance floor by my ex, who was pulling an extended "I'm breaking up with you slowly and refusing to talk with you about it" and my boyfriend-to-be who I didn't realize I had feelings for yet... that was a confusing feeling).