We did one day in each park in July and did not get park to park tickets, we stuck with the one park option. We enjoyed both days and didn't miss park hopping. In fact it probbably made use explore each park a little more and discover and enjoy some rides/attractions that we may not have done.
If WWoHP/FJ is your main reason for visiting - get to IAO before opening and ride FJ first and explore the WWoHP, do the rest of the park, then go back to WWoHP near park closing to ride FJ again.
Personnally I would save the money and have a nice meal in Citywalk after the park on one of those days. Also keep in mind that the parks close quite early at that time of year, park hopping would be good if the parks were open till late in the evening but maybe not so much when the parks close at 6 or 7pm.