24 teams spit into 4 divisions of 6 teams each makes the most sense. It would enable schedulers to continue regional rivalries and reduce travel costs, particularly for the non-revenue sports. Getting to 24 teams with an eye towards maintaining some regional relationships would require adding 2 more west coast teams, such as Stanford and Cal, and adding 4 east coast teams, such as Clemson, FSU, Virginia and North Carolina. All 6 have been rumored to have interest in the B1G or vice versa. The northern California markets would be covered, as would much of the southeast. For the Atlanta market Georgia Tech might be an east coast alternative with strong academics, but their football and basketball programs, the major revenue sports, have been sub-par in recent years. I understand there are a variety of issues with both Cal and Stanford, but if you are serious about creating a truly national conference some compromises will have to be made.
Nebraska and/or Iowa would be spared the travel to the west coast inherent in being part of a west division. Illinois, Iowa, Nebraska, Wisconsin, Minnesota and Northwestern as well as Indiana, Michigan, MSU, Purdue, tOSU and Penn State in two divisions would preserve historic regional rivalries. An east coast division would consist of Rutgers, Maryland, Clemson, North Carolina, Virginia and FSU. Much easier to run a 24 team end of the year basketball tournament than an 18 team tourney. In football four division champions would feed into a playoff for the championship, and someone with an imagination could come up with an also-ran playoff that would keep more teams playing into the post-season. Finally, scheduling and travel for non-revenue sports would be significantly easier. Under the present system the cost of non-revenue sports could become prohibitive.