Lisa,
If it were me, (and I had your ADRs), here is what I would do. This is certainly not the last word on a schedule, but like you, I like to hear what other people would do, as a comparison.
- August 16 - Magic Kingdom (all day)
- August 17 - Animal Kingdom (AM) / Epcot (PM)
- August 18 - Magic Kingdom (AM) / Hollywood Studios (PM)
- August 19 - Epcot (AM) / Open
- August 20 - Hollywood Studios (AM) / Epcot (PM)
- August 21 - Animal Kingdom (AM) / Magic Kingdom (PM)
For your open afternoon on the 19th, this is a great time to either hit Downtown Disney, a water park, your resort pool, or whatever park you are itching to get back to after your first 3 1/2 days.
FYI, don't feel like you HAVE to visit two or more parks in a day just because you have a park hopper. If you have only one reservation for a meal in a day, consider hitting just that one park, and think of your park hopper as
insurance in case your moods swing you to leave a park before your day is done!
Have a magical vacation!