Last year DH and I took out then 3DD and 1DD for 7 days at WDW. I also struggled with the question...to go back and nap, or not to go back and nap. I played it by ear on the first "park day" I was lucky my kids took naps in the stroller. I took our own stroller so they would be more comfortable. They napped for about an hour after lunch. It worked out so well that this became the plan for the whole trip. During their nap, my DH and I took turns riding the bigger rides or we would find a shady spot and rest and have an mickey bar. It was great! After their nap, we would resume all activities. We usually had an ADR for dinner and the kids did great in the restaurants. After dinner we would continue doing rides and things until about 9 or 10. The kids were so tired by the end of the day, they fell asleep quickly. We were tired too by that time and went to bed at the same time most nights. We did sit out on the porch a couple of nights.
Looking back, I think the short nap in the middle of the day gave the kids enough energy to get through the rest of the day, but not too much to keep them from sleeping at night. I liked it because I didn't feel like we wasted time traveling back and forth to our room at the Boardwalk. My DH and I enjoyed our "alone time" while they were sleeping.
We will try and do this again in April. I hope it works as well this year.
I know this only will work if one has children who can/will nap in a stroller. Having a child who is older makes it hard. I can't picture a 6 yo trying to get comfy in a stroller