For WorldCon 2009, I made Dizzy and Testament, from Guilty Gear. Both were hell to do, because of fake leather. And the terrible white make-up. And wings. Damn, if I have to do wings again, I need a costume that covers me better, so I can fix them better.
If I had known more about SF cons, I wouldn't have done this cosplay. But hey, it was fun, see all the people in the Green Room, talking, eating, dressing... it was a great experience. I learned a lot.