I've included the Google Maps route from Norfolk to Orlando.
Just from eyeballing it, it would be somewhere in South Carolina. If you're looking for a major city you could detour from the Google Maps route and hit Charleston, but out of cities listed here I'd probably go with Florence, SC as the city closest to the halfway point.
Murfreesboro, TN is halfway between Lyndon KS and Orlando FL
Kansas City, Missouri.
McDonough, GA
Walbridge, OH
Savannah, Georgia.
Byron, GA
Blumpkin City, FL
Hardeeville, SC is the halfway point between Norfolk VA and Ft Myers FL
There is approximately 1,301 miles between Boston, Massachusetts and Orlando, Florida. The halfway point is located in Rocky Mount, North Carolina.
Rocky Mount, NC
The best city between Atlanta, GA and Orlando, FL to meet might be Valdosta, Georgia which is about seven miles from the exact midpoint.
Florence, SC and Latta, SC