The Cabot Trail is worth the drive to Cape Breton. There are many outstanding viewpoints along the way, but there are also some steep grades and tight turns, that a larger motorhome would find "challenging". I saw a few larger motorhomes trying it, and recall wishing them "good luck" as we passed them in our Roadtrek.
Baddeck is a good base location to explore the rest of Cape Breton. There are some smallish cafes and fooderies along the various routes. Fuel is generally available along the trail, but will be pricey, and some stations will have shorter hours of operation, so best to run on the top half of the tank where possible.
When you cross out of the lower half of the province across the swing bridge and the Canso Causeway into Port Hawkesbury, keep a lookout for bald eagles. They sometimes nest on tall trees, and power and communications towers along the canal. You may see osprey nests as well. They've built special platforms for nesting for them along the highways.
If you like big boats, check out the ferry docks in North Sydney.
Take your time, and enjoy the views, it will be memorable.
If you do decide to visit the southern end of Nova Scotia, there's Peggy's Cove, and right near it, the roadside memorial for the passengers and crew on Swissair Flight 111 that crashed there in 1998.
Lots of other less infamous historical sites throughout the province.
