I've traveled up there on the way to and from Newfoundland. The jumpoff point to Newfie is North Syndey, NS, which is a nice town in itself. The east coast, Peggy's Cove, Lunenberg, etc., is most heavily touristed, and coming from Maine, it didn't really differ that significantly from the Maine coast, but it is more rustic. The Cat ferry is a real highlight, like being on the starship Enterprise, beautiful titanium fittings and a contemporary design icon. For me, Cape Breton was the spot I would have liked to spend more time, as we were heading back and in a rush already by then. We had traveled up the east coast, then back down the Cabot trail. Up in Cape Breton, there is a Celtic College that teaches Gaelic language and literature, and they have a music school as well. You might check and see if there are any events. It seemed pretty great and utterly authentic, and none of my forebears even remotely honked on a sheep's bladder or hopped a bog. Think the wesxt coast is the spot. Southern NS is fairly remote and unpopulated above Yarmouth through to Halifax. Bypassed Halifax, but heard it's fairly cosmopolitan.
Another thought-the town of Shubenacadie hosts vintage motorcycle races in late August or early September, way up in Cape Breton. You might find an event; there are tons of riders who will appreciate idiosyncratic machinery.
Canada is the place to ride, but watch out for wildlife and prepare to forsake fresh vegetables and cell service on the remote stretches. Find a way to keep your batteries charged on the bike - I would have liked to have more camera life, but I usually tent-camp. And bring a good rain suit.
In Portland, the younger euro bike cafe crowd hangs out at Amigo's, just down the strip from the ferry, tucked in on Dana Street. I will be in Maine next weekend, but not the next when you are there. We should do a NYC meet at some point too. I'm in Cobble Hill around the corner from the movie theater.
Best wishes. And don't forget to write up a ride report for us.