I still think 30 teams works best (although we could get left out from that).
Big Ten and SEC would consist of 6 team divisions and play 10 conference games. So you play regional rivals yearly and lose no games from the old setups.
B1G...
PAC 8 division- currently they have USC, UCLA, Washington, Oregon. IMO Stanford would make the most sense but you could argue Cal instead.
Big 8/WAC division- currently they have Nebraska. Potential fits are Kansas, Colorado, Iowa State, Arizona, Arizona State, Utah.
B1G West division- Wisconsin, Minnesota, Iowa, Illinois, Northwestern
B1G East division- Ohio State, Michigan, Michigan State, Purdue, Indiana
Eastern Indy division- currently they have Penn State and Rutgers (although you could argue having Maryland here). Notre Dame would fit. Then potentially Syracuse, BC, Pitt, UConn.
ACC division- currently they have Maryland. Potential fits FSU, Miami, GA Tech, Clemson, UNC, Duke, NC State, UVA, Virginia Tech.
SEC...
MWC/WAC division- potential fits Fresno State, San Diego State, UNLV, BYU, Utah, Colorado State, Boise State, Arizona, Arizona State, Cal.
Big 8 division- they already have Oklahoma and Missouri. Potential fits Colorado, Kansas, Kansas State, Oklahoma State, Iowa State.
SWC division- they already have Texas, A&M, and Arkansas. Potential fits Houston, Texas Tech, Baylor, TCU, SMU.
SEC West division- LSU, Mississippi, Mississippi State, Alabama, Auburn.
SEC East division- Florida, Georgia, Tennessee, Vanderbilt, Kentucky.
ACC division- they already have South Carolina. Potential fits FSU, Miami, Clemson, GA Tech, UNC, NC State, Duke, UVA, VA Tech, Louisville.
P5s with no shot- Wake, Oregon State, Washington State, West Virginia, Cincinnati, UCF.
States with no shot- Delaware, West Virginia, New Mexico, Wyoming, Hawaii.
I suppose you could include a third 30 team conference and have the 90 teams break away. Then you can include every state but Hawaii.
Leftover conference...
Two PAC/MWC/WAC divisions- potentially Oregon State, Washington State, Cal or Stanford, Fresno State, Boise State, Colorado State, San Jose State, Nevada, Utah State, Wyoming, Air Force, New Mexico.
Big 12 division- potentially Kansas State, Oklahoma State, Iowa State, Houston, Texas Tech, Baylor, TCU, SMU
Big East division- potentially West Virginia, Pitt, Cincinnati, USF, UCF, Temple, Louisville, BC, SU, UConn.
ACC/AAC division- potentially Wake, Duke, USF, UCF, ECU, Tulane, Memphis, FAU, Army, Navy, Delaware
Division of leftover leftovers- whatever makes sense from the above teams. Most likely a Big East/ACC/AAC grouping.
If you did go to 90 then you can have your conference playoffs consisting of the 6 division champs and four wildcards (10 of 30). Then have a national playoff with the 3 conference champs and two wildcards (5 of 90). That is a ton of playoffs, but playoffs is where the $ is made.