If you are traveling from the US, there is no need to change your money.  US dollars are used as readily as Bahamian Dollars in the bahamas and are equal in value.  If you are coming from another country, it's wise to change your money before you get to the bahamas.  Credit Cards are used throughout most of the bahamas, especially in the tourist areas, but some of the smaller out island require cash for purchases, and sometimes even car rentals.

ATM's are available throughout Nassau, Paradise Island and Freeport, but are harder to find in the smaller islands.  ATM's at the Casinos and near the Tourist Information Area give US dollars.  All others will dispense Bahamian Dollars.   Try and use your Bahamian dollars before you leave, some places may change it for you.. other will not.

Travelers Checks are accepted in most resorts and tourist restaurants and attractions.  Some hotels charge a small fee to cash them for you.