Teri,
I can't make it down to the civic center this year, but if I were going to go, I was going to plan on two days so I could see everything. You will have plenty to do during the day. As far as seating, you won't have trouble finding a place to sit. Obviously the earlier you line up at the door the better the seat.
It's snowing pretty hard down here in Bham right now and the streets will probably get bad tonight, so if anyone is headed this way, be careful.