Chances are good you have a sequin dress tucked away from New Year's past. Provided the neckline isn't boob-tastic, you can layer a skirt and blazer over it as a fun sort of suit. The trick is to wear sensible shoes, natural makeup and strong but simple jewelry. And to not work in a bank. Sequins give bankers frowny face.
A dress with simple lines can be punked up with awesome/ugly shoes, a deconstructed top and the right chunky jewelry. (I suppose you could do this with a foofy, but I'm just not as keen on it.)
Who doesn't love a retro party frock? (Really? Then you have no heart, madam!) Play up the 50s silhouette with an equally girly sweater (worn over or under the bodice) and cute flats.
Have you managed to break any party dresses out for the light of day?