Wear something you are comfy in, but is a little step up from your day-to-day wear so you feel glamourous as well! Have fun :)
(I'd go with a casual dress and your favourite heels, or just a plain top and jeans combo with great accessories)
I agree--maybe add a "conversation piece" of jewelry or another accessory (oh, I got this on my trip to . . . . my grandmother gave this to me . . . ). Good luck!