The U.S. dollar is accepted in most shops, restaurants and service stations at the current exchange rate. The vast majority of the establishments accept known credit cards: Visa, Master Card, Diners and American Express. Using traveler's checks is limited, it is recommended to consult on establishing whether they are accepted.
There are two types of places you may change your money, banks or exchange houses, the last being the one with best prices. In both cases it is very important to check the authenticity of tickets (without broken edges) before receiving them.
If you wish to carry traveler's checks, keep in mind that is not so easy to change, and some banks may require an extra charge for change.