J.B.
If you're going to Jacksonville, you might as well go ahead and go to Ponte Vedra or St. Augustine Beach. Jacksonville Beach is okay, but St. Augustine Beach is just more "vacationy" -lots of great seafood places, GORGEOUS wide beach that's great for all beach activities including bike riding and a beautiful old town with tons of history, a Spanish fort and a Spanish "castle"-Castillo San Marcos. Ponte Vedra is between the two and quite lovely as well.