The shorter park hours gave us an opportunity to rest, enjoy longer dinner shows, explore the Disney Boardwalk, etc. I'd recommend going to see the later showing of Hoop Dee Doo Revue. Also, you can add park hopper and go to a park that has later hours since most days have one park open later.
Because the crowds are so much less, we actually got a lot more done with the shorter hours than our trip in mid-July. I thought I'd hate the 5pm close at AK (for example), but it was actually quite nice! It prevented me from having that inner struggle between non-park fun and park fun.