I hope you like hills. This is the best reference for routes in Atlantic Canada. Their ratings and comments are quite accurate. Look for roads with a rating of 3 or 4:
http://www.atlanticcanadacycling.com...lon/index.html
I rode into St-John's from western Newfoundland
via this route and it was great. The Trans-Canada has a decent shoulder but there's lots of traffic and noise.