Most remarkable part, people laugh at dollars :) They're no good in Europe.
It may be a good idea to exchange currency before the trip, you might get a better exchange rate.
Switzerland accepts euros and Swiss franks, but will always return the change in franks. Lots of coins, too. When you try to exchange currency, though, coins won't be accepted.
Germany and Netherlands accept only euros.
American credit cards, mostly, don't work - American Express is rarely accepted, and the only version of MasterCard that is accepted (except for very few places) is the one with the chip.
The card that does work is Maestro, however, it looks like it's not a credit card, which defeats the purpose - unless you have a dedicated spending account. Also it looks like US version won't work anyway (no chip).
Credit card companies will charge what they shamefacedly call a "currency conversion charge" (2-3%). However, it will be charged on *all* transactions, including those made in dollars, so it is rather an "overseas charge" (they will reluctantly tell you this when you ask).
And, of course, cash will always work. Moreover, there will be places that won't accept credit cards at all, citing too much overhead.
One thing that is *very* different - in Amsterdam, I've been advised more than once that it would be a dumb idea to carry your wallet in your back pocket - pickpockets are ever busy in downtowns and on crowded trains.
^[European Chronicles 2013]