I saw the dresses ree-Xi posted and couldn't resist going to the same site...to me, these dresses would also be appropriate for pref:
This one with accessories and shoes similar to what the model is wearing would be really cute.
I LOVE this one, but you'd have to pick the right accessories to make it work for pref. I think nude shoes like these:
and some gold jewelry would dress it up enough.
And this is my favorite:
You could wear nude or black shoes with it and pearl or diamond earrings...that would look super classy.