We had no problems leaving the airport, but I got lost returning the car (and almost missed my plane home). So heed my warning, when renting car with off-site rental locations (especially fairly distant off-site locations like Atlanta), leave enough time to drop your car off!!
We were told over and over again, unless you wanted to wait in slow traffic, do not to mess with the Atlanta rush hour. We didn't -- the traffic was bad enough in mid-day and evening. One reason traffic is so bad in Atlanta is that three major interstates meet in downtown Atlanta, the I-85, I-20, and I-75, plus the city is ringed by I-285.
Once you get downtown, there appears to be two subways (the transit system is called MARTA) - one going north/south, and the other east/west. I never tried the subway. We stayed near the airport, and drove downtown, parked and walked around. Many Atlanta features are within walking distance - Turner field, Philips arena, CNN, Coca Cola tour, Atlanta Underground, etc.


