Hi Simon,
I live in New Brunswick, though have only been here a relatively short time, and on a touring bike even shorter. But there are many beautiful spots for touring. Nova Scotia, and Cape Breton in particular are wonderful, as is PEI (Prince Edward Island). There are many spots in New Brunswick - especially up and down the Fundy Coast (which is where I live), although the road surfaces are not always the best. We get a lot of snow, a lot of frost heaves, and the tarmac takes a terrific beating from the whole freeze/melt/freeze/melt cycle. But in general, the roads are clear and open, the traffic is very manageable, and people (including most car drivers) are friendly and courteous. I have not been there, but a couple of my friends have done a number of bike tours through Newfoundland, and absolutely love it - Gros Morne park being their favourite spot. Another favourite bike tour is around the Gaspe penisula, taking the ferry to Isle de Magdalen, and back to PEI .Finally, I just bought a book called "Motorcycle journeys through Atlantic Canada" by Rannie Gillis and Ken Aiken, and it has many great ideas for day and multi-day trips. Over the next few years I hope to become more acquainted with this lovely part of the world.
Best wishes for a great trip! Rick