I have no idea what it's like for you in FL, but here in MA, on professional days, of which we have three a year in the district in which I teach, we do things like:
-get trained in anti-bullying, or anti-racism adult education
-get trained in new curriculum programs, like writing, math, reading... this is not "planning", but learning how to use a brand-new curriculum
-get trained in new uses for and forms of technology
-work on vertical teams for a certain curricular area (K-5 teams)
-analyze data we have collected on kids and decide how best to help struggling students
-begin, continue with, and try to finish curriculum mapping, revamping of assessments, etc.
Most of the things we start in my district either never get finished or take a backseat for a while because they are always heaping new initiatives on us. The list I gave you is pretty short compared to the things we really need to get done... not that those items don't need to get done too, they just all get added to the same plate! We can't get any quality work done with kids in school or on half days when we don't have much time. I understand how this is an inconvenience for parents, I am one too and my daughter's school is where we live, not where I teach, so I have to pay her after school care more too. I can say as a teacher, however, it is necessary!