They don't want to stay near where the friend lives if they want to go to Turner Field and North Point Mall. Centerville is about 90 min south of Turner Field. My mother in law lives there. It's a tiny town of nothing but shopping and horrible, horrible traffic. The planners just allowed malls and stores to go up but didn't add any roads so going anywhere takes forever and yet it's a town of very few people. Yuck!
I would suggest looking in to staying near Duluth area. It won't take you long to get to Turner Field - maybe 45 min - and North Point Mall. My parents live near Duluth so I know that area.
Actually Duluth is in the North East of Atlanta and The AG store is at Northpoint which is on the north west side of Atlanta.
I have to tell you though, some of my friends who have gone there did not think it was so super. The shop and all is apparently great but the food not so much.
The Zoo is wonderful, my family has bee sponsors for years and it has become an really great place to visit. The ticket prices have shot up, but there are usually discount deals around. Check out
http://halfoffdepot.com/atlanta/
I grew up in Atlanta, and yes there is crime (big shocker for a large city right) and yes there is traffic, but there are some wonderful areas both inside and outside the perimeter you can stay at that would be nice to stay at.
I should have added earlier that the only area downtown that I would recommend you stay (although it would to be my first choice obviously) is around Centennial park. That is where the Aquarium, the Children's Museum and The world of Coke, etc are.
I also have to warn you that Atlanta is pretty spread out and you should consider renting a car.
I would recommend you stay in the Buckhead area. There are lots of shops and restaurants and it si pretty central to a lot of the Atlanta activities.
The Intercontinental has become the pretty popular hotel in Buckhead
http://www.ichotelsgroup.com/intercontinental/en/gb/locations/atlbh
It has a bunch of good restaurants and is right down the road from Craft and, my favorite, Dante's down the hatch (totally worth the splurge, even for the kids!
http://www.dantesdownthehatch.com/ ) and 2 malls.