East Cobb County is on the border of Fulton County (Alpharetta) and the real estate taxes are less (my lot is an acre and I pay $1300 annually in taxes...small house) and the schools are good (I've got kids). I've lived in Alpharetta and now live in East Cobb; the big issue in Atlanta and the surrounding area is how close you are to work. Traffic here is some of the worst in the nation and can really affect your quality of life. I work in Buckhead and it's a good hour each way....sucks!!!
As compared to California prices, the city of Alpharetta, East Cobb, the city of Woodstock and Cherokee Counties are going to be a dream come true for you.
Try to get in-town while you are here. Virginia Highlands, Little Five Points and Mid-Town are fun.