I'd say express yourself in a formal way. We were told to wear something appropriate for an evening wedding. My dress was black knee-length & sleeveless, with black sequins spaced out near the waist and they got less spaced as they went to the bottom. It wasn't flashy at all, but it made it a little different from a plain black dress. I could undoubtedly (sp?) wear it again to a nicer diner. I had two, and decided the day of which I would wear. They were Byer Too and Rampage if that helps any. I got both of them a department store. Just like everything, find a happy medium. Not too out there, not too boring.
Have fun
Heidi