We take about $500 in Tc's (for 3 weeks) and use our CC for the rest.

As people above have said this has been covered in depth before but what I think confuses some people is that most CC DO NOT charge you for using your card in the US they give you a slightly lower $ rate. On the other side of the coin they do give you cashback whereas others e.g Nationwide do not give cashback on foreign purchases. You need to look into your T&C's of your card to find out exactly what it will/will not costs you.