You're going to pay 2.5% fee whether on credit or exchanging for cash.Unless you're going to spend all the cash or planning on going back to the states,you're going to pay another fee again to change it back.Unless you see the dollar losing another 2.5 cents by the time you go,there's no advantage to bringing cash only.I'd bring some cash for little things but otherwise a CC.You're paying the exchange either way,but you're cc gives you the rate at time of purchase and only on what is charged.