I used to live in Coweta County, about 10-15 minutes from PTC and also did my flight training for my PPL at FFC.
It is true that PTC is probably one of the most expensive areas to live in, but it is very nice for the most part. Tyrone and the Stars Mill area are pretty good too and are a bit less expensive. General rule of thumb is that you probably want to stay on the west side of Fayetteville and south of Ga 54 as a general rule, particularly if you've got kids you may have to send to school one of these days.
Even though it would put you very close to ZTL, I would have to recommend against anywhere in Clayton County. Their schools are in the crapper, property values have tanked (currently Clayton is one of the counties with the highest rates of foreclosure in the Atlanta metro area) and crime is higher than quite a few other counties in the area. Its a shame, because that's actually where I'm from, although we moved out some 15 years ago now.