Forget AmEx. The French don't even like MasterCard. I learnt this last month, going there first time.
When I was at the metro station, tried using my MasterCard at automatic ticket machine, just won't work. So I went to the counter. I asked her if I could pay by card. She told me yes. Gave her my AmEx, and she said Visa. So I thought, OK, gave her my Earth+ MasterCard, since there is no commission on this WBC Earth+. She said no again. I was confused. So I asked again in case she was not good with English, and she said I could pay by plastic. So I repeated "No MasterCard?" She said "No, Visa". Now this is starting to sink in, so I shown her my Citibank Visa card, she said yes, but I need to use automatic ticket machines because she does not have EFTPOS at counter.
Guess what? My Citibank free for life Visa with 3.4% commission worked!
So I went to another restaurant, again, no AmEx, no MasterCard, only Visa.