Obviously the PA, OH, and eastern/northeast will be the biggest turnout.
The central area, won't be much very few of us with the largest rep coming from Texas. Vendors in the central won't be much if anything until Dallas. There you have AWDtuning and Cobb.
Defined is in Springfield, MO so that could be an option but would put Texas kinda far out. 7 hours drive from DFW and Texas being the biggest igota showing so turnout may be weak for the igota guys.
Buuuut still a few of us igota guys at a meet could rep and turn some subie lovers over to us.
Oklahoma has a nice track at Hallett but other than that, no vendors and a not so strong subaru community. I'd rent the track for us but monetarily I don't think the turnout would be enough to even recoup the rental if around 3k.