Even though Euros are not the currency in all your ports, most places near the tourist 'beaten path' will accept them. Just be aware you might not get a great exchange rate. I'd use a credit card for most things, and not worry about having a lot of different currencies. Get some walking around money at a bank ATM. You probably already know this, but let your credit card company(s) know about the cruise. Having foreign transactions suddenly start showing up can trigger a fraud alert and suspended accounts.