I'd like to put in a plug for my local favorite, the Ozark Trail. It is a named trail but seems to be under the radar for most people. The continuous part of the trail is over 200 miles so it fits your criterion. And it's gorgeous. Mostly oak/hickory forests (the hickory smell is awesome) interspersed with stands of tall white pine. Then occasionally the forest opens up into a glade which affords views of the surrounding hills. The terrain is quite steep in places and the geography varies from beautiful red Rhyolite in the Francois mountains to Sandstone and Dolomite further on. There are frequent creeks and streams and even occasionally great swimming holes.
Compared to the AT the great thing you will notice is the solitude. I very seldom see other hikers. And there are no mice-infested AT shelters you have to use. You can camp anywhere you like (as long as you aren't ON the trail). No backcountry permits either, just show up and hike.
Oh, and there are no bears to speak of. There are a few bears out there and everyone hopes to see one some day but most people never get the chance. I still hang my food but I don't worry about it much.
The main hazards of hiking in the Ozarks are the ticks. We don't have lyme disease that I know of but ticks are a nuisance. But a little permethrin takes care of that. I do see snakes now and then, occasionally a copperhead. But it doesn't take much to avoid them. The weather can be an issue. We get really strong thunderstorms occasionally which can be exciting. But that's part of the adventure!
The locals are also really friendly and helpful also. If they see you at a road crossing they'll almost always stop just to make sure you're okay. Really great people out there.
So don't overlook the Ozark Trail!