I did Springer to Harpers ferry in 99. My knees gave out. They seem to have recovered and I have given some thought to finishing when I retire, but I have come to the conclusion I rather prefer hiking more remote trails particularly in the off seasons when I can be alone.
The AT is sort of weird because besides a big hike its also a social event. Unless you very fast or very slow, your going to be walking with and sharing shelters with the same folks over a periods of days or weeks at a time. There are a lot of hikers on the trail especially if you do a mid march to April start on a NB hike,
Its not a wilderness backpack. To give an example how not a wilderness hike it is, when I started I carried the state guides and maps, but by the time I got to Virginia I just had one guide, mostly to shelters and off trail resources and a map on a bandana. There were so many people to ask questions of I probably would have ditched wingfoots guide and just used the mapdana.
Suggestions
Once you have done your research and followed blogs, whiteblaze etc and figured out a plan ( several ways to walk the trail S-N or N-S or a flipflop and thought out resupply etc, Find some 150-250 mile trail and walk it. and see what works and what doesn't. Then do two weeks on the AT in peak season and see if its what you want to do.
