This hike was very magical. And was my favorite of the three hikes I did in the Smokies. But also super, super crowded.The Smokies is a very car-friendly park (see the people just circling Cades Coves in their car amazed at some deer or a turkey) since it has no entrance fees, is the most visited park, and in an extremely car-dependent part of the country, but that means that I often found trails much, much lighter on people than places like Yosemite, which feel much more heavily traveled.
If you do this hike, go past the lodge on LeConte all the way to Myrtle Point. Better views than Cliff Tops and enough people stop at the lodge that it winnows down the people making it there even further. Most I've ever seen out there is maybe 5-6 other people, and typically it's only a 1-3 with some time totally alone if its off season or a weekday.
The most unique Smokies experience is surely the synchronous fireflies, which I've been lucky enough to see twice (once through the lottery, once through hiking in from the main road) and highly recommend.
Alum Cave to LeConte is my favorite hike in the Smokies though, even did it another time with my partner when we came back to TN to get married.