From the Blue Ridge Parkway, I'd go I-81 with stops to see Skyline Drive (we stayed at the Luray KOA) in Virginia and Harper's Ferry in WV (we also stayed at the KOA). To avoid NYC, stay on I-81 through Scranton PA, then take I-84 east to Newburgh NY. There is a KOA in Newburgh that is very nice and they have a bus tour into NYC or you can drive to the train station in Beacon NY and take the train into the city. Another side trip would be into WV to see New River Gorge. There is a COE park we like in Summersville WV on US19.