469 miles of ridge-line road with no trucks, no billboards and a 45mph limit.
The Parkway runs the spine of the Appalachians from Shenandoah down to the Great Smoky Mountains, and it's designed as a scenic road rather than a route — no commercial traffic, no advertising, a 45mph limit and an overlook every few miles. It's the most relaxing long drive in the United States.
It's also slow by design. Averaging 40mph means the full length takes a minimum of two long days of driving; four to six days lets you actually hike, which is the point.
This one works well with a group because the costs are low: no park fee on the Parkway itself, cheap cabins off-route, and hiking as the main activity. The catch is signal — plan the day's overlooks and the night's cabin before you leave town, and keep them on a shared plan you can read offline.