Places to go:
PEI for sure, it is like driving back in time. It really is quite different than the mainland. PEI national park- Cavendish campground is excellent. See some of the sights right around the park, bike the trails around the park, eat some seafood in North Rustico and visit Charlottetown.
New Brunswick: Bay of Fundy National Park
Nova Scotia: Cape Breton Highlands National Park- drive the loop around Cape Breton for sure.
We took hwy 1 last summer and it was an easy and scenic drive and it takes you right past Fundy. The only concern about hwy 1 is that I saw no Service centers or Truck Stops along the way. I had to get gas in town in St John and the gas station I went to was quite busy and very tight. My wife had to guide me out and stand in front of the cars of the fools who thought they could zip past me to grab my pump while I was still trying not to sideswipe any pumps or cars. But that was just one crappy gas station on an otherwise excellent trip.