Even though we call it "prom," most people stick to fancy cocktail attire. Boys wear suits (not tuxedos), and most girls wear short dresses, not traditional poofy prom dresses. I actually wore a DVF minidress to my prom (in 2007...I feel old), but I sort of regret not doing the long dress thing.
I'm planning on wearing this navy one-shoulder Shoshanna dress. With these shoes. The jury is still out on a bag. I'm thinking about a dove grey Rebecca Minkoff mini MAC, but I'm not totally sold on that idea yet.
Any bag suggestions for me?