THE Maritimes is 3 provinces: NB, NS, & PEI.
Atlantic Canada includes Newfoundland and Labrador. So, if you go to NL, best you know this. Newfoundlanders, especially care about this. & that you say Newfunland, which rhymes with understand.
You need a minimum of 3 weeks for Newfoundland and that is just a teaser. Gros Morne National Park, The Northern Peninsula including world heritage site L'Anse aux Meadows, Trinity Pageant, St. John's, St. Mary's Bird Sanctuary for a few. They who live in Port aux Basques, where you land, say it is a 12 hour drive to St. John's.
Nova Scotia has many pretty places too. IMHO, Cape Breton Highlands National Park's Cabot Trail is nothing in comparison to Gros Morne. The reconstructed fortress at Louisbourg is essential. It's living history. Historic Halifax. Bluenose II, which is being restored again. Bay of Fundy.
New Brunswick. I disagree re. Kouchibouguac. In getting too crowded it's deteriorated. Many other good things. Acadian Historic Village is also living history, tidal bore, Fundy National Park, offshore islands - Grand Manan, Deer Island, Campobello Island. Saint John City Market. Hartland covered bridge.
Prince Edward Island. Historic Charlottetown. Orwell Corner Historic Village, living history including livestock with their babies for kids of all ages, Charlottetown Farmer's Market (esp. Saturdays), New Glasgow Lobster Supper - dare I say Anne, and beaches. If you do Anne, don't ask where's she buried. Given that's she's fiction, that drives the staff nuts.
August is hottest, temps stay up over 21'C at night. AC if you have problems with that.
:B