Summary of alternate alignments
(1) Near-geographic alignment: Revised crossovers from the OP. All but FSU/Miami and UNC/UVA could rotate every schedule cycle though.
ATLANTIC/COASTAL
Clemson/Louisville
Duke/Syracuse
Florida State/Miami-FL
Georgia Tech/Pittsburgh
NC State/Boston College
North Carolina/Virginia
Wake Forest/Virginia Tech
(2) Compromise alignment: Not geographic, so NC-4 are split, but improves annual matchups over existing alignment (e.g., Miami can play BC and Syracuse, Louisville can play Pitt, FSU doesn't have to make as many trips to the Northeast).
ATLANTIC/COASTAL
Clemson/Georgia Tech
Florida State/Miami-FL
Louisville/Boston College
NC State/Wake Forest
North Carolina/Duke
Pittsburgh/Syracuse
Virginia/Virginia Tech
(3) Alternating pairs alignment: Similar to compromise alignment, but BC+Louisville and Pitt+Syracuse alternate between divisions every 2 years. The 4 alternating teams all play one another every year. Permits full conference playthrough for all teams in 4 years max.
ATLANTIC/COASTAL
Clemson/Georgia Tech
Florida State/Miami-FL
NC State/Wake Forest
North Carolina/Duke
Virginia/Virginia Tech
ALTERNATING
Boston College/Syracuse
Louisville/Pittsburgh
(4) Alternating trios alignment: The pods of 3 alternate between divisions every 2 years. Each team in a pod of 3 plays its pod mates and a protected crossover in the other pod of 3 annually, and all other teams an average of once every 2 years. Each team in a pod of 4 plays its pod mates and a protected crossover in the other pod of 4 annually, the teams in pods of 3 an average of once every 2 years, and the non-protected teams in the other pod of 4 an average of once every 3 years. Downside: besides potentially confusing fans, prevents annual Clemson/FSU matchup, which may be a dealbreaker.
ATLANTIC/COASTAL
Clemson/Georgia Tech
NC State/Wake Forest
North Carolina/Duke
Virginia/Virginia Tech
ALTERNATING
Boston College/Louisville
Miami-FL/Florida State
Syracuse/Pittsburgh
(5) Divisionless alignment: Unlike the other scenarios, this would of course require an NCAA rule change to implement if the ACC wants to retain its CCG. However, near maximum schedule variety and minimum conference playthrough time while maintaining the most important annual matchups. Each team has 3 protected opponents (below) and alternates between half the other 10 every 2 years.
Code:
BOSTON COLLEGE Syracuse Miami-FL Pittsburgh
CLEMSON Georgia Tech Florida State NC State
DUKE Wake Forest Georgia Tech North Carolina
FLORIDA STATE Miami-FL Clemson Georgia Tech
GEORGIA TECH Clemson Duke Florida State
LOUISVILLE Pittsburgh Virginia Tech Syracuse
MIAMI-FL Florida State Boston College Virginia Tech
NC STATE North Carolina Wake Forest Clemson
NORTH CAROLINA NC State Virginia Duke
PITTSBURGH Louisville Syracuse Boston College
SYRACUSE Boston College Pittsburgh Louisville
VIRGINIA Virginia Tech North Carolina Wake Forest
VIRGINIA TECH Virginia Louisville Miami-FL
WAKE FOREST Duke NC State Virginia
NOTE: In all scenarios, I've worked with the existing 14 football members, kept the conference schedule at 8 games, and tried to maintain competitive balance. Let me know what you think! Can you come up with some better solutions besides the existing alignment?
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BONUS!
If the ACC were to go to 9 conference games, having 2 protected crossovers might be feasible. Consider my near-geographic alignment (#1) under this scenario:
Atlantic
Clemson: Louisville, Virginia Tech
Duke: Syracuse, Virginia
Florida State: Miami-FL, Louisville
Georgia Tech: Pittsburgh, Miami-FL
NC State: Boston College, Pittsburgh
North Carolina: Virginia, Syracuse
Wake Forest: Virginia Tech, Boston College
Coastal
Boston College: NC State, Wake Forest
Louisville: Clemson, Florida State
Miami-FL: Florida State, Georgia Tech
Pittsburgh: Georgia Tech, NC State
Syracuse: Duke, North Carolina
Virginia: North Carolina, Duke
Virginia Tech: Wake Forest, Clemson
Most of the crossovers are arbitrary, so with this alignment it's probably better just to stick to one protected crossover and have 2 rotating ones.
My "compromise" alignment (#2) under this scenario:
Atlantic
Clemson: Georgia Tech, Miami-FL
Florida State: Miami-FL, Georgia Tech
Louisville: Syracuse, Virginia Tech
NC State: Wake Forest, Duke
North Carolina: Duke, Wake Forest
Pittsburgh: Boston College, Syracuse
Virginia: Virginia Tech, Boston College
Coastal
Boston College: Pittsburgh, Virginia
Duke: North Carolina, NC State
Georgia Tech: Clemson, Florida State
Miami-FL: Florida State, Clemson
Syracuse: Louisville, Pittsburgh
Virginia Tech: Virginia, Louisville
Wake Forest: NC State, North Carolina
All 4 NC teams get to play each other every year, as do all 4 southernmost teams, while retaining balanced divisions and without requiring pods. And double conference playthrough (home and away) in 10 years instead of 12.
BTW, the Coastal here is the private schools plus the "Tech"s, while the Atlantic is all the non-"Tech" public schools. This was not by design, although I don't much see a downside. It might even help some fans remember the divisions better.