What he said.
Find Canton draw a line along GA-20 over to Cumming.
Anything South of that is a disaster waiting to happen and I don't recommend living there.
Also, take "best schools" with a grain of salt. All over metro ATL you will hear parents at the local Waffle House brag their rug rats go to the best school in their county and what they are saying is their kids go to the best out of the worst schools in the county. Georgia public education is a joke compared to a private education, and it's a joke when compared nationally to other state's public eduction systems.
I was at a party this weekend with several "old" friends in their 30's and 3 of them will be downloading within the next 6 months. Every last one of them already is planning and saving for a private school including Woodward which is something like $16K/yr now. Ridiculously expensive but worth every penny. These aren't wealthy couples either...these couples have high 5, very low 6 digit household incomes.
While I don't have kids, I would live in a re-po'd single-wide and walk to work before my child received a Georgia public education.
Just my .02