One little note on that...make sure to read the fine print regarding credit card rental car insurance. Many cards have a pretty hefty deductible. A 'gotcha' that gets those same people who don't read the fine print of their airline travel terms and conditions and find out the hard way to always read your paperwork!

As for OP, I usually use a combination of visiting a currency changer at the airport (stateside) that offers discounts/waived fees for airline and airport employees. Then ATM's in country if I need more.