For apple picking head to Ellijay in N. GA -Gilmer County. Mercier Orchards near Blue Ridge is nice too. Call ahead though and see what hours they have, etc.
My highest recommendation is for Southern Belle Farm in McDonough GA. It's FANTASTIC!!! Hay rides, huge slide, giant corn maze, a REAL pumpkin patch where you go pick your pumpkin off the vine, a cow train, farm animals, a corn cannon and pedal go carts are some of their offerings. It's pretty and so much fun! Burt's in N. GA is a crowd scene and their pumpkins cost a fortune! They're also already picked and they don't have nearly as many activities as they do at Southern Belle. It's south of Atlanta -about 40 minutes. Have fun! I've sent tons of people to Southern Belle and everyone has always had a blast. We go every year! Look on their website because they also have bonfires at night on the weekends. Our boys are still too small and go to bed early, but I can't wait to try that.