My AAA guidebook for the Carribbean notes the official currencies in use on each island, and also notes when the U.S. dollar is also in such wide use that you generally needn't worry about converting money for tips or small purchases. The notes for St Kitts (Eastern Carribbean Dollar; 2.7 to the U.S. dollar) and Dominican Republic (Dominican peso; 35 to the U.S. dollar) don't mention this, however. (Given the enormously strong immigrant ties between the D.R. and the U.S., I assumed the dollar would be accepted nearly everywhere tourists might frequent there!)
Any CM staff have any thoughts on the D.R. and also St Kitts where the U.S. dollar is concerned?