Bad Daddy's in the Charlotte airport has a good burger and drink menu for slighly jacked-up airport prices. If you've got at least an hour to burn at CLT, it's a decent place to spend it. They've got plenty of TVs playing NASCAR and baseball to keep you entertained between flights.
While it is an airport restaurant, it's definitely on the better side, but it's still an airport restaurant. It can get pretty crowded during the lunch rush, with business travelers, families, all with suitcases and backpacks everywhere. Service isn't quick, so if you don't have much time before your next flight, you might wanna hit up a different fast-food joint. But if you are looking for milkshakes or mixed drinks, this is probably your best choice!