Just wanted to close this topic down with a trip review based on all of your recommendations!
Day 1: Shenandoah National Park. Stayed at Big Meadow campground and had a great time. The bear fence rock scramble was the highlight. Amazing hiking.
Day 2: Luray Caverns. Stayed at the falling waters RV park off I-81. Meh.
Day 3 (July 3rd): Went to the Gettysburg reinactment and spent the day between the battlefields and the visitors center. Fun! Drove to Knoebels amusement park and got there at 8 PM. Walked around a bit before the park closed at 9.
Day 4 (July 4th): Spent the day at Knoebels. Lots of fun, very cheap. I think we spent less than $100 there and had a great day with lots of fun. Stayed there that night too.
Day 5: Drove to Hammonasett Beach State Park in CT. Great sunset, easy walk on the beach, nice campground.
Day 6-7: Drove to Atlantic Oaks RV park on Cape Cod. Excellent location, easy in and out, bike trails for the kids, beaches close by. Stayed there 2 nights.
Day 8: Did a whale watch in Provincetown. Lots of waves that day and half my family got sick, but we got to see a bunch of whales! Drove down to Hyannis and watched a cape cod baseball game that night. Easy parking for RV's there at the high school. We got there about 90 minutes before the game and parked really close, made dinner, enjoyed the evening at the ballpark. After the game we drove all the way around Boston and spent the night in a Wal-mart parking lot around midnight just after crossing into New Hampshire.
Day 9: Drove up to Old Orchard Beach. Unfortunately it rained for 36 hours as soon as we crossed the Maine border. But luckily the lobster was still delicious. Stayed at Paradise Park RV resort in OOB. It was very nice and would certainly stay there again when the weather was better.
Day 10: Drove up to the Schoodic Penninsula and stayed at the new Schoodic campground. Wonderful new campground, big sites, easy bus pickup for travel around. Schoodic point is very cool.
Day 11-12: Drove to Acadia and spent two nights at the Blackwoods campground. We did quite a bit in 3 days in Acadia. Took the kids on the "Dive In Theater" with Diver Ed. Highly recommended! Drove up Cadillac Mountain in the RV even though signs said we weren't supposed to (you can do it, it's not that bad).
Day 13: Drove to White Mountains in NH, did the Cog Railroad up to the top of Mount Washington. Stayed at Sugarloaf 1 campground which was nice and quiet. Would stay there again, especially if I had more time for hiking. I could hear a river close and I wanted to explore but the time just didn't allow.
Day 14: Drove to Burlington and did the Ben and Jerry's factory along the way. The tour is ok, nothing special. But the ice cream was great! Spent the night at an uncle's house.
Day 15: Drove to Saratoga and walked around the National Military Park. Kids got another junior ranger badge and we got out of the RV for a bit. Drove the rest of the way to our family reunion in Binghampton, NY.
Day 16: Drove home.
Overall a fun trip.
Best Lobster was actually not in Maine but at Arnold's on Cape Cod. I had two excellent lobster rolls in Maine too (and two mediocre ones). But Arnold's was the best.