We went with the FULL intention of midday breaks. Sun, we didn't take one, 2 year old slept in stroller, rest of us took it easy in the pm. Monday, MK, we did. DH and I slept, the DD's didn't. We ended up with a much crankier child that day. To our surprise, she slept much better in the stroller than going back to the room. For us, sleep, not just rest, made the difference for her. So we stayed in the parks, gave her plenty of chances to nap in the stroller, and used middays to visit some A/C places, longer lunches that we weren't really hungry for, but enjoyed the break from the heat and crowds. Yes, she fell asleep at dinner a few times, during our Wishes cruise, and sitting for an hour before Fantasmic. Did I care? Nope, b/c she was getting what she needed. Our nine year old did GREAT with no room breaks, in fact, best week of our lives.
So.... make a plan, and be prepared to change it daily! We didn't have much problem rearranging ADR's once there to make things fit into our schedule, mood at the moment! (Cancelled two, added two, change time on one..)