I keep one MBNA card just for foreign charges. It is significantly lower than other cards most of the time. I just got a notice from Citibank, too, that they are getting ready to institute a 3% conversion charge. I avoid foreign ATM's;it seems easier just to convert a few American $100 bills at a time(I do have a favorite money-changer in Paris, who is fairly close by and gives competitive rates). For travellers who spend a lot of time in Paris, a euro account with a Carte Bleu might make more sense. It has gotten easier for Americans to open these accounts(particularly if you tell the bank officer that it's for business). Carte Bleu is really an ATM(not a credit card as Americans know them), but there is no charge from any ATM I've ever used.
(I take that back;Belgium is different).