With a boat, there are lots of spots. The best spot for your purposes would Curry Hammock State Park in Marathon. Lots of shallow water and a great site for the day with restrooms, grills, shade, grass and sort of sand. Better for beginner thru advanced where Bahia Honda is better for intermediate and up. Awesome local crowd too to help you out.
oTHErside Boardsports
www.othersideboardsports.com
305.853.9728