I'm probably very much in the minority here, but I think it is worthless to go back to the hotel for a nap. Our Sept. 2004 trip we had DS3.5 and DS7 months. Our May 2005 trip We had DS4 and DS15 months.
We did not go back to the room in Sept. and the kids just napped in the stroller (DS#1 quit napping at about 2- 2.5). It was wonderful. We did follow their pace. If things weren't going well, we did 180.
In May, I was also 6 months pregnant. Definetly planned on going back to WL for naps/breaks. And for the first 3 days, we did so. We had to fight with the kids to get out of the parks. Fight with them to go back. It was miserable. No one was having a good time. Then, we spent day #4 at the park all day. Taking in shows, switching parks, sitting down in A/C for lunch (long if need be), taking a train ride (or two) around MK, shopping while the kids napped in the stroller, Tom's Sawyer's Island/Bone Yard/Donald's Boat etc, etc whenever anyone needed a break. This day, EVERYONE had a great time. So, we followed suit for the remaining 6 days. Worked out much better. No whining. No arguing. No complaining. We just let the kids set the schedule (different from home) on when to get up and leave, when to come back to the hotel, when to nap, when to eat. The rest of the trip was heaven.
Breaks, yes. Out of Park? NO! My advice is follow your gut once you get there. If things in the park aren't working out for you no matter what you do, leave. Don't push kids beyond their limits--ever. But don't feel forced to keep them on the same schedule as at home (mine change schedules when we get there and switch back the day we get home all on their own), follow their leads on wants, things they dislike, hunger, etc. THAT is what makes a successful trip, IMO.