To clarify AA's odd way of defining "international," I found it best to look at it geographically.

Basically, "international," in terms of upgrades, is anything outside of the North American continent (ex. JFK-LHR, ORD-CDG, DFW-EZE, etc). These are not eligibile for sticker upgrades.
http://upload.wikimedia.org/wikipedi...rthAmerica.png

Hawaii is a bit of an oddity in that I don't think it officially belongs to any continent, but it's politically part of the US and it's eligible for sticker upgrades.