Since rumors of expansion has risen again, here is who I would invite if I was King:
BYU- large, loyal, national, underrated fan base. Mega eyeballs. Scheduling around Sundays is not a deal-breaker.
Cincinnati- Big media town, travel partner/rival for West Virginia.
Central Florida- Every school gets to travel to (and recruit) Florida!
Tulane- Every school gets to travel to NOLA! Downside- Tulane might not want to associate with Tech academically.
I know, that would be 14. But the Big10111214, the ACC and the SEC all make 14 work. It can't be that hard.
Besides- when the next big shakeout comes down there won't be enough chairs for the Big Time Football Lotto Payout Table for every school that wants in. This group includes Iowa State. But squatters have rights, and it will be much harder for a league to toss out a member than to pull in a new one. Better to start on the inside.