ATL is my preferred airport - Not positive, but you will probably leave out of Terminal E which is a very spread out terminal, often with lots of walking. Very doable. The train is quite reliable and easy to access. A tip if you have to use the train - after you get off the escalator, board the 1st or 2nd car of the train. When you get off those 2 cars are closest to the up escalators. Nice to know if you have tight connections.