The Hiker Hostel in Dahlonega, GA near Woody Gap is pretty nice. The people there are former thru-hikers of the AT (GA-ME '00). They provide a great deal in terms of shuttles and specials. It is even possible to walk the AT all the way through Georgia with just a Day Pack on your back while staying at the Hiker Hostel if that appeals to you. Imagine, a warm bed each night – a good breakfast (AYCE) each morning and dinner out in the Gold Rush Capital of the south each evening at a different restaurant. Look them up! www.HikerHostel.com and see for yourself the facilities and accommodations.
The Taxi fare alone is at least $60.00 from Gainesville, GA to Amicalola State Park and the Hiker Hostel offers a better deal.
Of course, it is possible to get to Gainesville, GA by train from Atlanta and then walk the 20 (or so) miles to Amicalola or try to hitchhike but it is a very iffy thing.
Skylander