Just some random ramblings. I’m drawing on some 30-year-old memories, so there might be some mistakes.
I’ve never heard them called the Shenandoahs before, and I’ve spent a lot of time there. So you might ask the locals if they call them that. The mountains are generally called the Blue Ridge, and the Shenandoah is the river that runs north-south to the west of them. Shenandoah is also the name of the national park that runs from Front Royal south to the Blue Ridge Parkway. I don’t remember exactly where the name change occurs.
The Blue Ridge is not particularly wide, and the Skyline Drive runs along the ridge, and of course it’s a national park, so there’s nothing very isolated about it. To the west, in the valley and ridge, things get a bit more isolated. To the southwest, in North Carolina, even more so.
The forests in the park are quite young. Before the park was created, in the 1930s IIRC, the area was largely denuded by loggers, and by people doing subsistence farming. There are also some small copper mines. Everyone was thrown off their land to make room for the park. There are still traces of old buildings, but not as many as you might think.
Topographically, the area is not very rugged compared to, say, the Smokies. The mountains become higher toward the south, though never very high, and the rocks become somewhat more metamorphosed. So in the north, the rocks are quite blocky, whereas to the south it becomes more phyllitic. The peaks are generally, though not always, the Catoctin Greenstone, a metamorphosed basalt. The geologic structure is a large anticlinorium (concave-upwards fold with lots of smaller folds within it) which has been thrust eastward along a large fault zone. The shallower western limb of the anticlinorium is the Blue Ridge, while the steeper eastern limb is essentially the lower ridge called Southwest Mountain. The rocks themselves are Precambrian. There have been several periods of mountain building, starting with the Taconic Orogeny in the Ordovician.
One interesting area is Big Meadows, which is around mile 50, and was once a chestnut forest. The chestnuts were all killed by the blight, but even recently there were still some pretty high trunks, because chestnut has a high tannin content.
There are a few nice hikes in the area, especially Old Rag Mountain (long hike) and Stony Man (short hike).
You can get publications by the US Geological Survey on the park and its surroundings, which also talk a lot about the fauna, some about the flora, and some about the culture of the area.
Hope this helps a little.