Don't let people charge you in US Dollars. When they do that, the conversion rate they uses STINKS. It adds so many extra points. You are much better just paying in the local currency and taking the conversion fee hit from your Credit Card issuer.
We have traveled, quite literally, all over the world. What works best for us is to use credit cards for big purchases (hotel bills, furniture, whatever) and then pull large chunks of cash out of the ATM for everything else. Lots of seasoned travelers swear by the Capital One card.
Just let your bank and credit card companies know ahead of time that you are traveling so they don't freeze your account for strange purchases. Also, call your bank and get your ATM withdrawl limit temporarily increased so you can pull more cash out the ATMs each day.
Have a great trip