You will get a small drop in temps <5 degrees on Lookout Mountain, Cloudland Canyon SP or DeSoto SP. Close to 10 at Fort Mountgain, campground at 2,400'. Really need over 2,000' of elevation to see much of a drop. That's why Cloudland and DeSoto don't have cooler temps, their only 1,800-2,000 feet in elevation. Vogal SP is about 2,200', and has heavy shade. Also the sun goes behind the mountain early. Black Rock Mountain is the highest at 3,640'. But they only have small sites, and the road up is very steep and crooked. Amicalola Falls campground is about 2,600'. But again the road up is very steep, 20% steep.