Aruba currency is the Aruban guilders (AWG) or Aruba florins (sometimes abbreviated as AFL.) At the time of the last update (Sept. 2012) the exchange rate (U.S Dollar) is about 1$ to 1.79 AWG. This rate has not fluctuated for over 10 years. The US Dollar is accepted at most places on the island, and other currencies may be exchanged at local banks.
Local bank hours are weekdays from 8:00 a.m. to 4:00 p.m. Some banks close during lunchtime (12:00 - 1:30 p.m.). Some are open longer on Fridays (until 5 or 6 p.m.) The only bank open on the weekend is the Caribbean Mercantile Bank, located at the Queen Beatrix International Airport. (open 10 a.m. - 6 p.m., Saturday and Sunday.)
Traveler’s checks and Major credit cards are accepted at most establishments. There is no fee for using traveler’s checks, but the banks will charge a fee for cashing them.
When we needed cash for our parasailing excursion, we learned that the hotel casinos were more than happy to cash a traveler’s check (if you give the impression that you are going to gamble with it… We cashed a $100 traveler’s check at the Stellaris Casino in the Marriott, and played a few nickel slots before leaving.)
The ATM machines will accept debit cards with Cirrus, Maestro or Visa logos. But, again, most dispense the local Aruba currency.
Be aware that only the hotels and the main tourist areas will give you change in U.S. dollars. You may end up with a pocket full of Florin at the end of your trip.