Ok, Im really on the fence about us adults dressing up now. On the one hand, its our DD birthday on that day and we want to make it special for her and get into the spirit of things but on the other hand I just know when Jay see's that not everyone will be dressing up he'll probably feel a bit silly. Hmmmm, what to do.
If you want to dress up then I think you should! There will be other people dressed up, just not everyone. Same as formal night - just because everyone doesn't dress up doesn't mean I won't (and make dh dress up too, lol).