I was in that area a few years ago. In New Brunswick be sure and see the Hopewell Rocks where they have the 45 foot tides. In Novi Scotia there is Peggy's Cove. Also Cape Bretton Island. Since you are only charged to leave PEI, I would plan on taking the Ferry to PEI and the bridge back. Probably save about 35 or 40 dollars as on the ferry you are charged by the foot to leave, but the bridge is a flat rate.
Also get a good local map for Nova Scotia, We got lost there may times due to the poor road signs.
On PEI we stayed a Scotia Pine RV park near Green Gables, and they gave us free passes to use for Green Gables tour.
I GOOFED on the campground. It was Glasgow Highlands, near New Glasgow. :o