Yes that is a great area for trout streams, in contrast to you the Catskill rivers were closer to me (lived in Northern NJ) so I focused on them and only occassionally went to PA. But PA is a great trout fly fishing state. Last time I actually fly fished them was also the early 1980s, either 1981 or 82 and is I headed straight to the West and main branch of the delaware. Did not see another angler.
Drove through the area 5 years ago on way from Cooperstown down to NJ for a family event, and the Beaverkill, Delaware, Willowemuc area looked the same thank god not much more commercial development etc.. Have to get back their again for some fly fishing, before I leave the planet, if you know what I mean.
Some great FF memories from that area, will write some up in the essay thread when I get the time this winter.