We live in the tri-corner area of Gwinnett, Forsyth and Fulton counties. This is the 10 mile radius where Duluth, Alpharetta, John's Creek and Cumming all meet. Sugar Hill is also nearby and is comparable. It is the top rated area for metro schools.
We chose to live in Forsyth county section because the taxes are substantially less than Gwinnett and Fulton. The school system in Forsyth is not considered a "metro" system (because Forsyth county isn't considered a metro county) so you won't see it on any metro-school lists but it is the highest rated school system in the state. As a mom I can tell you that the family amenities in this area are some of the best around. There are so many things to do and places to go. Forsyth and Gwinnett are also known for their great park and recreation systems.
You will find that homes in Forsyth cost less and have more square footage than those in Fulton. As for traffic, it just depends in Atlanta - we measure everything in time not miles. When I lived in Gwinnett I worked in an office 16 miles from my home and my commute was right at 50 minutes. I had another job that was 46 miles from my house and took me 40 minutes. Traffic is our curse!
If you send me a private message with exactly what you're looking for, I will be happy to point you towards some specific planned communities. There are just so many at so many price points. We have one next to us, Long Lake that started in the $200's and a mile down the road is Creekstone that starts in the $1million. There is everything in between form $90's on up. Forsyth and the Duluth/Sugar Hill section of Gwinnett have a tremendous variety of real-estate for almost any price range.