I've only been to one con so far, but I wasn't in costume. (I-Con 22 in Stony Brook, NY) So it's my first time cosplaying, too. But I'm going as Rinoa, and hopefully, my b/f will be going as Sephiroth. Were going on Saturday only, however.
And FFX-2 seems to be the most popuar cosplay right now, so I wouldn't worry. xD