In Spain you can pay with credit card almost everywhere. You will be able to pay by credit card in taxis (ask before you get it), restaurants, shops, pubs…
The best way to get cash is by withdrawal. Therefore, we don’t recommend you to bring too much cash.
Ask your bank about commissions for withdrawal money from ATM in Spain. The commission you are charged to withdraw money from ATM is set by your bank, so please check with them before you leave.
Also, ask your bank if there are banks that will accept easily your credit card and go directly to them. In Europe we use “Chip and Pin” credit cards and sometimes US credit cards don’t work in some ATM’s. If this occurs, don’t worry, we have many banks and ATM’s, you just have to identify the one that works with your credit card. If you ask your bank, this will be easier.