Interesting history piece on the SEC and ACC expansions 20-years ago:
1990-1991 SEC Expansion - Arkansas & South Carolina join Southeastern Conference | Saturday Down South
Seems as if the SEC was trying to shore up Florida with Miami and FSU and/or get into Texas, but kind of failed on both fronts and ended up with Arkansas and South Carolina. Looks like Florida State had their choice of conferences and Bowden preferred the ACC due to it being perceived as an easier path at the time, while Miami felt their fanbase and prospective students were more likely to come from the Northeast, so they went with the Big East.