I have been based out of ATL since my move from So.Cal. there are many things I love about flying AA out of ATL. The entire staff is great, including those at the AC club.
The AC club is fine, I usually only spend less than an hour there, the friendly staff makes up for more than the "old and dark" image.
Leaving out of the t-gates is so easy, no train required, and if you are checking luggage
(I have not in 4 years) the baggage claim is great.
Since all my flights are international , I have no problem with getting to a gateway city given that I have many choices.