Not sure what your financial situation is like, but if you look in to some of the neighborhood schools in certain Atlanta areas you can likely get in to city life for the same cost as Newnan or Peachtree City in terms of house. There are people raising families in the city and enjoying themselves quite nicely. My sister lives in the city there and sends her son to a great public school (baccalaureate school). I think you could get in to that district for less-than-mind-blowing home prices and be 15 minutes from ATL. Admittedly, I don't know all of the angles for school considerations, but parts of Decatur are pretty nice, too, and less of a cookie-cutter suburban feel if that is a consideration.
Peachtree City is okay, but really showing its age in areas and it is not quite what it once was. I lived there for all of my school years pretty much and it was great 20 years ago, but has changed in a lot of ways. I go through there now from time to time and just can't believe the traffic and growth.
Newnan is just the epitome of suburban waste land to me. Now, I do tend to lean toward city life because of more unique businesses, restaurants, parks, etc, and Newnan is the polar opposite of that paradigm. It just started to explode about 10 years ago and everyone who would have once lived in Peachtree City moved instead started their families in Newnan and it's just crazy there now. But, again, very little with much of a personality. It is still full of rednecks just like it was 20 years ago, but some of them drive mini vans now.
I can't really help you much with the Northside of ATL, I haven't really spent much time in that area, but I would look in to The Vinings, maybe even Marietta or West Cobb County.
One thing I'll say about it in general: Don't let anyone kid you, traffic is just as bad in Peachtree City or especially Newnan as it is right, smack dab in the middle of Atlanta. I lived in the city for years and was never really that put off by traffic. Especially if you don't have to be on the road at 0800 or 1700.
I hope that helps in some way. Good luck!