WOW....Thank you everyone. It looks like a lot of good information and it will take me some time to go though it & all the links in detail.
DH and I have traveled to the east coast a couple of times in an RV and have been to the New England states once in 2009. We avoided toll roads then because we don't mind taking back roads and we know that there are bridges/tunnels we can't go on because of our propane tanks, but I'll have to review our route from our other trips.
Places we've been to but really want to repeat because our friends haven't been are:
Boston, MA Freedom trail
Arcadia National Park
Appomattox Court House National Historic Park, VA
Smokey Mountains National Park (a must see for our friends)
White Mountains & Kancamagus Highway in NH
Other places that we are considering that I didn't mention before (depending on route we take):
Mammoth Cave National Park
Shenandona National Park, VA
Congargee National Park, SC - the only one on this list we haven't been to yet.
We have all been to the Liberty Bell, Independence Hall and Gettysburg before but repeating those locations are not off the table at this time.
AZ Buck, Our friends are on a trip right now and we just decided to plan this trip together last weekend so I'm not sure of all the places they are interested in. NYC & Washington DC being two of them. We are going on a trip with them at the end of August and will have plenty of time to discuss where we all want to go. I'm just doing some basic research right now.
I will definitely check out the "Notches" you mentioned!
Donna, We're not planning on Florida this trip.
Thanks again and I'll keep you posted on what our plans will be.