The AT is an incredibly well maintained trail. Spaced along the trail, all about a days hike apart, are shelters built and maintained by trail volunteers.
We haven't been sleeping in the shelters but it is always nice to camp nearby because of the excellent bear bagging system. A long steel cable is strung between two trees with four bag hooks on pulleys along the cable. Bears can't reach it (I try every night to jump and touch our food... while doing my best bear roar of course) and can't bite or tear through the cables attached to the tree. Very clever indeed!
Mouldering toilets are another great feature. The waste is kept above ground and is composted.