Blankets Creek is a singletrack trail network with 6 trails: South Loop, Dwelling Loop, Van Michael Trail, Mosquito Flats, Mosquito Bite, and Quehl Holler. This trail was designed and built by the Southern Off Road Bicycle Association (Woodstock). As such, it is a very, very VERY popular mountain bike destination. The parking lot is packed out every weekend, and it stays very busy even during the week. Just be aware that if you choose to go here, you will be dealing with a lot of mountain bikers.
From I-285 go North on I-75 to I-575 north. Go to Sixes Road-exit 11 and turn left (west). Trail is about 2-3 miles on the left and is clearly marked with plenty of parking.
http://www.tripleblaze.com/trail.php?c=3&i=216