I only know Nova Scotia.
Be aware that NS only has about 1 million inhabitants, and half of those live in or around Halifax. So there are vast stretches of thinly populated land, where you won't find shops or gas stations, and even might have difficulties to get a signal on your mobile phone.
Please be aware that many tourist sites outside Halifax (e. g. all the manor houses) usually are only open from June 1st till September - some close at the start of September, others at the end, and some in between. So make sure to check their websites.
When you enter NS by car, Truro is a city you inevitably come across. I never checked out the city itself, but you should go to Victoria Park and walk to the waterfalls, they are well worth it.
Then you've got to decide which way to go first - I guess going west first is more suitable for you?
At Windsor (that's the Windsor at the Bay of Fundy, not the other Windsor next door, closer to Halifax) you can see the Haliburton House Museum, a nice small manor house. Other "attractions" include the prize winning Giant Pumpkins of the Dill family; the "Hockey Heritage Centre" (just a tiny room inside the Dills' pumpkins shed); and the lake where - allegedly - hockey has been played for the first time (short walk from the pumpkin farm, i've been told).
You should drive to Wolfville, with its nice university buildings and its interesting botanical park. See Prescott House Museum nearby (Starr's Point), a smallish manor house. Then go on to Annapolis Royal and see the Historic Gardens.
Personally, I skipped the Yarmouth-Sherbourne end, so I can't tell you anything about it; I went straight through Kejimkujik National Park, where you can spend some time with outdoor activities.
You then end up in Bridgewater (a central town with supermarkets and stuff).
Between Bridgewater and Halifax, you have a couple of picturesque tourist destinations, perfect for photos: Lunenburg (with its iconic architecture), Mahon Bay (with its three churches), and the famous lighthouse at Peggy's Cove.
Halifax is a fun city, but you can see it more or less all in 2 days, basically.
Places to see include the Parliament and the Citadel. Then there's the area called the Historic Properties. And there is a huge art museum, if you like that sort of thing ("Art Gallery of Nova Scotia").
Halifax is quite good for shopping, but it is a city built on a steep hill, so walking around there is no fun. The shopping area ends near the Public Gardens, which is a nice little park. worth spending a couple of minutes there.
Also, the huge underground Farmers' Market is a must-see, if you are there on the right day of the week - but it is very much over-crowded.
Just outside the city is the Mount Uniacke Estate, which is the biggest of Nova Scotia's historic manor houses, as far as I can tell.
Driving from Halifax to Cape Breton Island, you can go the fast way via Truro, or you can go along the southern coast, where you have miles of beautiful landscape, and the re-created historical village in Sherbrook, but it takes forever! It is one of those routes of which the guidebooks say that you are likely not to have a mobile phone signal there, and that you should completely fill up your car with gas before travelling, because there are NO gas stations. Plus, if you miss the ferry on the road between Port Bickerton and Isaacs Harbour you're screwed, because it's the ONLY way! There is NO alternative road.
Directly after you've crossed over to Cape Breton Island, there are the only bigger supermarkets in Cape Breton (with the exception of Sidney).
Cape Breton is a beautiful place, but not much to see there. Their main attraction is the Cabot Trail, one of the most beautiful scenic drives in the world. Guidebooks say you can enjoy the Cabot Trail more by travelling it clockwise, so you are not constantly driving on the outer edge of the road along those cliffs. Less stressfull driving = more enjoyment of landscape.
Again there are no real towns, and no gas stations or food shopping opportunities after you've left Cheticamp.
When I was in Cape Breton, I skipped Louisbourg & Sydney, so I can't tell you anything about them.
Some advice about driving in Nova Scotia:
*** The Trans-Canada-Highway turns into a little road in Cape Breton all the way up to Baddeck (gets better again towards Sydney) - add dozens of trucks, plus steep hills, plus lack of overtaking opportunities --> and you will need a good deal longer to reach Baddeck than you'd think.
*** Avoid the so-called Glooscap Trail (i. e. the coastal road) between Summerville and Truro. It's utterly boring and costs way too much time. The other half of the G. T., between Truro and Joggins is much more beautiful, but also costs too much time. If you want to see that coast, I strongly recommend you only follow the G. T. between Truro and Parrsboro (or the other way round).