Cocoa Beach is just over an hours drive from Orlando with lots to do in the immediate area. Great beaches, some nice restaurants, malls, Daytona and Kennedy Space Centre is nearby. Theres all the standard US hotel chains on the beach offering good room rates.

St. Augustine is further north, about 3-4 hours drive from Orlando, it's Americas oldest city with lots to see and some lovely beaches. It's certainly well worth a visit.

On the west coast, the Naples area is another great beach resort. Have a look at this thread for more on Naples http://www.orlando-guide.info/forums/topic_28745.asp