Unless you want to hit big cities, we took I-95 to Richmond and then I-64 to
I-81 to Scranton PA, then I-84 east. If you want to see New York City, stay at Newburgh NY KOA and either take the train into the city from Beacon train station or take the tour bus from the campground. You can either head toward Boston or go up into Vermont and New Hampshire which we preferred. Stop at Cabot Cheese Factory and Ben & Jerry's in Vermont. See Quechee Gorge in VT. Stay at the KOA in White River Junction. Harpers Ferry WV is interesting. KOA nearby. I would make reservations for weekends and holidays, otherwise call ahead that day and see if spots available and arrive at campground early. About 3pm. We drive about 250-300 miles per day. If we drive more we leave earlier so we arrive by 3pm. We have plenty of time to rest, have dinner and maybe sightsee before dark. Other things of interest: Savannah GA, Gettysburg, Charlotte Motor Speedway NC, Washington DC (but that takes a long time to see). You didn't state your Maine destination but Bar Harbor and Acadia National Park is a must see. We stayed at The Narrows Too RV Park. The shuttle stops at the park and takes you into Acadia National Park.