While in Atlanta, be sure to go to Stone Mountain. The bas-relief carving of the Confederate Generals on the side of the solid granite mountain is worth the short trip... especially at night. There's a Swiss made cable car that runs to the top where there's a small restaurant. You can see three states from there.
There's also a 5 mile long train ride that's seemingly cheesy but it's actually fun... especially if you've not been on the railroad. Several other things to do in the Park.
Additionally, one can spend at least half a day in downtown Atlanta at the Coca Cola museum (you heard me right).
Interstate Higway 285 completely circles the city of Atlanta and takes about 2 hours to drive around. Stone Mountain is off that highway on the east side of the cirlce.
The Atlanta History Center is in Buckhead... on the northwest quadrant of the cirlce. It's extremely interesting and Buckhead has the best eating establishments in or near Atlanta.
Lastly, it's about a 75 mile drive north from Atlanta on Interstate 75 and 575 to Blue Ridge, Georgia, but it's one of the most beautiful, forested mountain drives you'll ever take. Lotsa things to do and see on the way... (there's amuch longer locomotive powered railroad there... about 25 miles long)
Best of luck and welcome to the U.S.!