So, Henry County is SE of the city of ATL, and straddles I-75, a major north-south interstate. The center of the county is about McDonough, which is ~30 miles south of the center of the city of Atlanta. Commuting north into the city between 7am and 9:30am is going to take you through some of the worst traffic; figure a 5-7 mile backup every day if you're a single person in a single car--you can save some time in the carpool lane. (Or, depending on where you're working, you can park near the airport and grab MARTA from there--not sure it would save much time, though.)

The good news about being on the south side is access to the airport (it's great) and the beaches (both the Atlantic Ocean and Gulf of Mexico are ~4 hours away). But access to the mountains is a little harder (places like Blue Ridge and Ellijay are great getaways when it gets so hot and humid in the summer).

Good luck with the relocation--it's great that you're able to take this step, and with the right attitude, it doesn't matter WHERE you go, you'll figure out how to fit in and have fun!