Matt - a fair number of hotels are willing to advance you some cash when you are paying by credit card. I discovered this once when I'd booked a ride on the complimentary hotel bus to the airport, spent all my foreign cash & then the bus left early - without me! I was furious, but the receptionist was quite calm about it, and simply added $xxx to my bill and gave me the cash in local currency. This is useful to know if/when you realise that you need more currency than you thought you would - and you get the benefit of the better credit card exchange rates.

Taking some US cash/travellers cheques wouldn't hurt either, as an emergency backup.