I have the BMO US Mastercard with 0.5% cash back. I had the option of Air Miles, but the cash back is a better deal. There is also a higher cash back percentage, but there is a fee for that card, I forget how much. Mine is no fee, and for the < $500/yr I charge on it, it's the best deal for me. (I have to use a corporate card for all my business travel.)

My BMO statement is in US funds, and I pay it by transferring money from my US chequing account or my US BMO Investorline account. No fees, no exchange rates to deal with.

Don't know about other foreign lands.