Many people go during that time, but should be prepared to quickly leave the islands if a hurricane threatens. Make sure which currency it is. Some resorts accept personal checks, so we take a few of those too. However, some resorts automatically add a service charge to their rates. In this case, you have no obligation to tip extra.
Some people do tip individual staff members who do something extra, or sports instructors.
If you scuba dive, it's always appropriate to tip the divemasters. One of the best ways to see the islands is to either hire a driver for a few hours or the day, or rent a car and drive yourself. This is just opposite of driving in the U.S. and takes a little getting used to. The first time we ever drove in a British island, my hubby pulled out on the road and was fiddling around with the windshield wipers. After that little incident, he stayed on the left side of the road.