A simple sheath dress or suit with gorgeous shoes and accessories can also save you from maxing out a credit card for a one night only outfit and be appropriate too. Your date can don a sports jacket or suit I would still question going sans tie. Men should wear dark suits. The overall feeling of fancy-schmancyness depends on the circle of people. Ultimately, you can choose whatever length you like as long as the style is elegant.
Men can wear either a dark suit or a tuxedo, but no sports jackets please.
This is where Mrs. Gotrocks goes to the vault. And for all you divas of decadence, this is one of the few occasions where you cannot be accused of being too overdressed. However, there is nothing worse than being inappropriately underdressed at a black-tie only affair. Rent a tux, if you don't own one, but please conjure up something innovative if you can't master the real thing. Opt for something simple and let your accessories take center stage.