If you are traveling to Grand Cayman you won't have to worry about finding a bank or an ATM to use, no matter where in the world you are from. The capital, George Town, is a major offshore financial centre and many banks are located there. As you travel out of town there are ATM's normally situated in supermarkets. It should also be noted that the majority of retail businesses and restaurants accept the major credit cards; MasterCard, Visa and American Express. All retail banks offer a counter service and are generally open Mondays to Thursdays 9am-4.00pm and Fridays 9am-4.30pm. Some banks are open until 6:00pm and Cayman National Bank (CNB) even opens a few of its locations on Saturdays. 

The official currency is the Cayman Island Dollar and you will see this expressed as either KYD, or CI$.  The US dollar is also accepted everywhere at a fixed rate of CI$0.80 to US$1.00. If you make purchases with US dollars you will usually receive your change in Cayman Islands currency.