I am just going to tell you what I wore last year when I rushed and you can just pick and choose. This might be easier than vague descriptions....
round 1: I wore a white skirt from Aeropastle and a blue t-shirt and Dr.Scholls sandals. I fit right in. Not too dressy not too shappy
round 2: I had a long blue wrap around skirt that I wore with a white t-shirt and blue flip flops. And I am not talking dressy flip flops I am talking comfortable Wal-Mart flip flops.
round 3: Just a little sun dress with white tennis shoes...like keds. That's right keds. You're feet and your face will hurt..at least something can be comfy.
round 4 (preferance): I wore a red dress, but the list they gave us suggjested black cocktail dress. A lot of girls wore black, the red definatly made me stand out.
The main point is to be comfortable and just have fun. Whatever you pick will be fine. I hope the list helps everyone out there who is going through rush. Good luck to all of you!