A few tips that you may find helpful if you are climbing Clingman's Dome via the Appalachain Trail from Newfound Gap:
Newfound Gap is an easy (3.5 hour) drive from Atlanta, so doable as a long day-trip if you are staying there. The Newfound Gap trail (actually the portion of the Appalachain Trail that parallels the auto road from Newfound Gap) is really the only trail to the summit that is practical to hike in one day, short of driving to the top and walking a half a mile from the parking lot. As noted in the main Summit Post write-up, the other routes are well over 20 miles roundtrip. Actually, even the Newfound Gap trail is a bit long for a day hike (7.9 miles one way, 15.8 miles rountrip, per the trail signs), particularly if you have a long drive on either or both ends of the day, as we did.
For some reason, the main write-up doesn't mention where to find the trailhead. It's across the road from the Newfound Gap parking lot and not terribly visible until you are right on top of it. We were fortunate to run into a ranger, who pointed it out. Be careful not to pick up the other side of the Appalachain Trail, which is better marked with a big sign adjacent to the parking lot. That will take you in the opposite direction, away from Clingman's Dome
The vertical rise from Newfound Gap is nothing special (~1600 ft) but be aware that there is a fair amount of ascent and descent in both directions, so the actual gross elevation gain is probably more like 2500 ft. The flip side of this coin is that trail is very well maintained. It's well graded and comparatively smooth, so hiking poles are not necessary and you can make pretty good time.
If you are pressed for time, as we were (we started from Newfound Gap at close to noon), you can shorten your hike by proceeding part of the way up the auto road to Clingmans Dome and parking your car at one of the two places where the trail touches the road. The first reduces the one-way hike from 7.9 to 6.0 miles and the second reduces it to 3.8 miles. Because there is no mention of this in the main write-up, we didn't discover these shortcuts until we arrived at the first parking pulloff. We elected to backtrack to Newfound Gap and take the car to the second pulloff. So, we ended up shaving only 4.4 miles off the roundtip hike. But made a huge difference. Even with our late start, we were able to get back to Atlanta in time to grab dinner.
If you are like us, you will probably be hurrying to the trailhead in the morning and disinclined to stop on way up to Newfound Gap. Take some time on the way back to pull off at the scenic overlooks and take some pictures. The views are spectacular and the low angle of the evening sun makes for great photos. These opportunities are welcome because the views from the trail are frustratingly few until the very top, and even there visibility can be poor due to low clouds.