The idea I like most is an Atlantic-Pacific Coast Conference by attempting to raid the PAC-12.
Take the 14 teams we have now, add USC, UCLA, Oregon, & Washington. That gets you to 18. With the addition of Notre Dame's primary rival, you make it more enticing to them. The goal is to get to 20 by adding one more (assuming you can convince ND... big if).
With the last spot, you can go for rivalries vs. TV markets. Take WVU and you get some great old school Big East matchups. Take Navy to get a very strong service academy and you make it more enticing to Notre Dame to join. Plus, you add the Navy vs. Army game every other year and ND vs. Navy at least every other year from a TV standpoing.
At 20 teams, you have 4 pods with something like the below (this is pretty unbalanced, but you get the idea):
GT, FSU, Clemson, Wake, NC State
USC, UCLA, Wash, Oregon, ND
UNC, Duke, Wake, UVA, Louisville
Miami, BC, WVU/Navy, Pitt, VT
Travel isn't ideal for the west coast teams, but they get at least 4 games on the west coast against teams in their pod. Then the remaining 4/5 games are split home/away, so they're only leaving to go east for 2/3 games.