Eh, it's in Dallas, right? So typical. No event in Dallas can be normal, can it? Everything has to be special! and personalized! and unique! Whatever. (I've gone to a few Dallas events in my life, if you can't tell.)
I'm sure you've already decided what to wear, but I'm fairly certain it means don't dress like an old lady. I'm sure whatever type of cocktail attire you choose will fit in appropriately. And if I had to guess, I'd say you'll be way classier and more fashionable than your fellow party-goers.
I bet you'll have fun though. Restraunteers know how to throw a party!