Room for everything?

One question I had about my cruise this year was answered with a little web surfing. The cruise is having two formal nights. I need to try on my suits to make sure they still fit. If not, I'll buy a new suit closer to cruise time. The cruise is 280 days away!

I hope my suitcase will have enough room for my clothes, a suit and two costumes. The group I'm sailing with has two themed parties scheduled: the first is '70s and '80s themed, and the second is a basic Halloween party. I thought about just getting a "Save Ferris" T-shirt for the '80s costume and bringing my panda kigurumi for the other.