Prefs = black cocktail dresses for the most part. I remember one year, we all wore black "dressy", and it was too much leeway for some folks, and people ended up wearing black jeans, next to a girl in a black prom gown! If your chapter is on a campus where semi-dressy is ok for pref, I'd do something with your colors. Wine and blue aren't they? They look good together.
I like the sash thing someone said.