American Express accepted in Switzerland

American Express is not as widely accepted as Mastercard and Visa. Because Amex wants to become more popular they have a deal with most banks that results in customers getting the Amex for free as a second card when they sign up for a Master (or Visa) card. And my bank even gives more points on Amex then MC, so I try to use it as much as possible.

And so I do know that it is accepted in quite a few cases. Generally large stores do, as do the Coop and Migros grocery stores. The railways accept it too, but the Swiss Post for example not. Smaller stores often do not accept it.

I always use a bank's ATM to procure local currency.

Locarno is on Switzerland, so you need francs. You could pay with EUR, at a worse exchange rate and get your change in francs. Like using USD in Canada.

Put your travel funds in a Schwab online account and use any ATM in the world for free.

Don't expect Amex or Discover to be widely accepted in Europe. Focus on a mix of Visa and MCards from different banks because inevitably for no apparent reason during your trip some will be rejected.