Florida State would never be invited, because the SEC already has a school in the state of Florida. I think the plan going forward on any expansion is expand into new states. Texas A&M would certainly rank high on the list, being that it would give the SEC entry into the state of Texas. Oklahoma would be a new state and a team with grand tradition. Texas would probably be the #1 target but they're never joining, and I'm thankful for that. I can do without their extremely overinflated sense of self-worth.
I think other targets would be Virginia Tech, Virginia, Duke, and North Carolina. Obviously, you may not get any one of those teams without also taking their rival. However, expansion is going to happen. The Big 12 is not made to last, and this huge tv contract Texas has secured for itself only hastens the conference's demise. You can bet the new Pac 12 still has its eyes on Texas, Oklahoma, Oklahoma State and Texas A&M. It's going to play out one way or the other and the SEC will do well to get at least two of the castoffs.