Yeah, I'd say that when I lived in Marietta, it certainly seemed like the Dawgs were a MUCH bigger deal than the Falcons. Maybe that changes when the Falcons are good...
I can definitely speak to LA. UCLA and USC were the only game in town, football-wise. So when they were good, all of a sudden they were beloved. When they're not, well then nobody cares at all. USC has tiny enrollment so almost nobody has a direct relationship to the school unless you're rich. UCLA is bigger, but it's still a drop in the bucket enrollment-wise.
Agree with Badge that the Lakers and the Dodgers are bigger draws than either, but of course neither one is football.
I'd say that's all changed. LA already had a contingent of Chargers fans, will always have a contingent of Raiders fans, and now the Rams are the draw.
From here forward, if USC is not in the regular national championship discussion, they're not going to move the needle in LA. UCLA IMHO will never be that in football, but might return to that level of prominence in basketball, and that'll be what is necessary to move the needle there.
LA is a pro town.