A year ago, prior to signing on here, I actually hashed out the expansion options for the PAC 10 fairly thoroughly. This analysis included an introduction, football stats (two years out of date), academics TV Markets and other sports, and a look at how I would make a convoluted schedule.
I concluded that Utah and BYU were the best fit then. Both teams have only improved their case since then.
Texas and Colorado are included in the assessment, but are ruled unlikely for various reasons. The remaining teams in the PAC 10 footprint are Boise State, BYU, Fresno State, Hawaii, Idaho, Nevada, SDSU, San Jose State, UNLV, Utah and Utah State.
While Boise State is a solid football program, they have little else to offer. Hawaii is really the only other university worth mentioning.
This leaves us with, BYU, Colorado, Hawaii, Utah and Texas as the serious contenders.