Whether you're the one bestowing the award, receiving the award, or attending the event, the best cue for what to wear to an awards ceremony might come from girls--they know that a special occasion calls for something special, whether it's a sparkly pair of earrings, a fancy updo, or a colorful dress.
It's not that you can't wear business attire, but to me it doesn't convey a true celebratory spirit.
Of course, this doesn't mean you should wear club wear either. Your heels should be whatever height you feel comfortable in for walking across a stage--probably not towering. Your dress shouldn't be too revealing nor too short. Ideally you're wearing something sweet, something that would make your family sigh with pride & joy.
Here's what I wore:
It's not often that we take the time to celebrate our accomplishments, & it's not often that we have a reason to dress up. Award ceremonies are by nature a bit awkward, but they're also infinitely memorable. Try to wear something you'll remember when you look back on the event years later.