My mind starting running this morning over realignment so I put something together that I thinks makes the most sense geographically while maintaining current rivalries and regional cultures. I ended with 4 conferences with 18 teams each, or 8 divisions with 9 teams each. I tried to put at least one "blue blood" in each division. There are currently 64 teams in the P5 conferences so 8 teams needed to be added - Notre Dame, BYU, UCF, USF, Boise State, Colorado State, UConn, and Cincinnati. Figured each team would play 10 conference games (8 divisional + 2 cross-divisional). Each conference champ would be guaranteed a spot in what would hopefully be a 8 team playoff.
Atlantic Coast Conference
North Division - Boston College, Maryland, Penn State, Rutgers, Syracuse, UConn, Virginia, Virginia Tech, Wake Forest
South Division - Clemson, Duke, Florida State, Miami, NC State, North Carolina, South Carolina, UCF, USF
The North Division consolidates all the northeast schools and adds Penn State whose alumni base is concentrated on the East Coast (Philadelphia, NYC, DC) rather than the Midwest. The South Division trades Georgia Tech for South Carolina to make the respective in-state rivalries divisional games. UCF and USF are added to consolidate with the other two Florida schools.
Midwest Conference
East Division - Cincinnati, Indiana, Kentucky, Louisville, Michigan, Michigan State, Ohio State, Pittsburgh, West Virginia
West Division - Illinois, Iowa, Iowa State, Minnesota, Missouri, Northwestern, Notre Dame, Purdue, Wisconsin
The East Division consolidates regional basketball rivals Cincinnati, Indiana, Kentucky, and Louisville and maintains the Michigan/Michigan State/Ohio State rivalries. Pitt and WV are added to renew their rivalry. The West Division adds Notre Dame, Iowa State (natural rival with Iowa), and Missouri (natural rival with Illinois) to many of the current Big Ten West teams. Admittedly Notre Dame would not be wild about joining this group of teams, but too bad.
Western Conference
East Division - Arizona, Arizona State, BYU, Colorado, Colorado State, Kansas, Kansas State, Nebraska, Utah
West Division - Boise State, Cal, Oregon, Oregon State, Stanford, UCLA, USC, Washington, Washington State
The East Division is easily the worst from a football perspective, but it consolidates a bunch of current and former rivals. Nebraska is added to renew rivalries with KU/KSU/Colorado. BYU is added to create a rivalry game with Utah for 4 in-state rivalries within the division. The West adds Boise State who have a semblance of rivalries with the current pacific northwest teams.
Southeast Conference
East Division - Alabama, Auburn, Florida, Georgia, Georgia Tech, Mississippi State, Ole Miss, Tennessee, Vanderbilt
West Division - Arkansas, Baylor, LSU, Oklahoma, Oklahoma State, TCU, Texas, Texas A&M, Texas Tech
The East Division adds Georgia Tech to renew historical rivalries with UGA and Auburn. The West Division takes the Texas and Oklahoma teams and adds former SWC rival Arkansas and cultural fit, LSU. The UT/Aggy game gets back on the schedule and Aggy gets to play divisional games against actual rivals.