Most of the issues have been well covered already. However, if you're in AA's program with an address outside the U.S. (I'm not sure how Canadians are treated in this regard) I believe you get AC/FL access within North America as well, even on purely North American itineraries. The reasoning seems to be that, if you're in North America, you are by definition on an international trip.

Whether or not this is still correct, and if it is whether or not all the lounge staff know it, and if they don't whether or not it's worth the hassle of convincing them, are still valid questions.