I would have to say, a floor length gown is a must. I went to a friends cotillion ball here in Texas ( I actually went to about 10 )...and they would check at the door and I know one of my friends wasnt let in with her knee length dress, and she looked VERY classy. Just think of Gone with the Wind..haha. The South is STILL stuck in the 1940's when it comes to debs.