Gale, I just saw your post & didn't know when you were leaving but I live in Snellville which is beside Stone Mountain in the Atlanta area. My husband & I both worked downtown years ago & there is no really great way around Atlanta.
As others said, it really is best to stay off I-285 because of the trucks & it's like a raceway-except when there is an accident & those are very frequent.
One of my son's works downtown & he put an app on my IPhone called Waze that tells all kinds of stuff to help you in driving. We used it last week traveling to FL & back & were glad to have it. It tells where accidents are, traffic & other things to avoid & ways around.
Have a good trip.
Joyce T