I lived in south central Kentucky for about 8 years, just about an hour north of Nashville. East Tennessee may be somewhat different but don't expect the summers to be that much cooler than Florida. I had friends in Kentucky who lived in Florida at one point and they both said the heat and humidity was much worse in Kentucky than it was in Florida.
In Florida you have the ocean breezes working to make the weather more comfortable which you don't have in Kentucky or Tennessee. Also, it was not unusual for the temperature to be 95 with 80% humidity or more for two or three weeks straight until a tornado producing thunderstorm rolls through. In Florida, from what I told, in the summer it's humid but the daily rain blows most of the humidity out of the air.
Just something to think about.
I would also argue against the four distinct seasons thing but that's really all in what you're used to. I really consider that area of the country to have two seasons. Fall and Summer.