I also crossed on the AT but not on a complete hike through.
Hiked over Clingmans Dome on my 1995 AT thru-hike. This was a new "elevation record" for me at the time.
Since I couldn't find any reasonable hiking information before arriving at the park I just drove to this summit - a problem that SP goes a long way to fixing ;-). Although I didn't find any snow, I was pretty surprised at all the rime and clear ice I found - in fact it only took a few minutes before my car windows were completely coated with ice (no visibility) once the sun went down. I was lucky enough to have the summit tower to myself on both the evening of the 4th and the morning of the 5th. The scenery and views were amazing though my photos should be rescanned sometime.