Rivnuts from Homestead, PA on 12/9/2021 7:56:39 PM:
I'm not currently planning the trip you've outlined, i.e. Pittsburgh to Great Falls (aka Seneca) over six days but have made a handful of trips between Pittsburgh and DC in recent years. Hence if I were making your trip a couple of itinerary options you might consider with daily mileage listed are as follows:
00 Pittsburgh
46 Perryopolis
58 Rockwood
44 Cumberland
60 Hancock
52 Shepherdstown
58 Great Falls (Seneca)
00 Pittsburgh
59 Connellsville
57 Meyersdale
60 Paw Paw
57 Williamsport
45 Brunswick
31 Great Falls (Seneca)
You can look under the "Towns and Services" tab in this forum for lodging and restaurant options in each of the overnight destinations. I've stayed and eaten at several of them. Depending on budget and preferences your choices may be quite different from mine.
I'm sure others will have some other suggestions as well.
May is a great month to make the trip. Not too hot and not too cold and accommodations are a little easier to get before the peak summer touring season.