Speaking of Eastern Ontario - Ottawa Valley, has anyone else been to the park under the bridge between Hawkesbury (ON) and Grenville (QC)? I'd say, that's something too.
@Acajack: I've always found the view on the super-2 section of A50 more breath-taking than that on 417. If that super-2 were twinned, I'd use that as my route between Montreal and Ottawa - Gatineau much more often.