Hope I didn't raise a ruckus with my original posting. Really the only point I was trying to make was that we had the problem coming back into the states from Canada. We've never had a problem getting into Canada (it was so easy we didn't think about it until we had a problem coming back!). My opinion is better safe than sorry and to carry proof of citizenship anytime you might want to cross the border. Believe me, a military ID doesn't necessarily help since I showed mine.
Just wanted to make sure we all get to have a great time!