We are early risers and are usually anxious to hit the parks early so AM EMH makes sense for us. We also like to park hop, rarely spending an entire day in a park, so once the park with the AM EMH gets too busy, we head back to the resort to relax and then hop to another park. Sometime we will hop to a park that has PM EMH so we can stay late, particularly when Epcot and MK are open late. We had some very late nights on our last trip.
Our next trip is during a very slow time of year with short hours so we will probably take advantage of both the AM and PM hours but with the PM EMH being an hour shorter starting in January, well see how well that will work. Guess there wont be any really late nights on our next trip and with the shorter hours, we may not take as long of a break, unless DD is really grumbly but if she insists she doesn't need to nap and she is behaving, we will skip nap time.