Thanks Everyone for the replies. When I ordered the ticket yesterday from Disney, the CSR told me that 90% of the people going to the party are in costume! I'm glad I checked with my friends here first before I thought about finding something.
I like the idea about a halloween t-shirt, I need new shirts, so I'll have to find one to wear that night. I'm going 09/29 so hopefully there were be just as many not in costume as there are in costume.
7 days from right this minute I'm hoping to hear..."ladies and gentleman the airplane doors are now closed, please refrain from using any cell phones until we have arrived at our destination and are off the active runway" I spend way too much time on an airplane!