Agree that it really depends on the child. Our first with-kids Disney trip had a barely 3 year old and a 2 month old. The 2 months old was MUCH easier than the barely 3 year old. But he was a challenge at home. He actually was slightly less of a challenge at Disney, but it was still a lot of work. We learned a lot that trip about touring with kids - so much that we went back 6 months later since we wanted to apply what we had learned. Before that first trip, we had agreed that we wouldn't go to Disney until the kids were completely out of strollers. So, it couldn't have been that bad! Our youngest had a trip at 2.5 years old. He has some sensory issues so it wasn't typical as he wouldn't do many of the rides. But he still had a lot of fun. He was more laid back than my eldest was so that helped quite a bit. We also were juggling three kids but it still wasn't all that hard - though we had a few with-kids trips under our belt by then.
For us, taking a mid-day break has never worked. My kids don't nap at that age. Even when younger, they wouldn't nap when we went back to the room. So it was wasted time. We learned that we can't get our kids to nap while on vacation at Disney, but we could get them to sleep at night at a reasonable hour. So, we had to do a lot of early nights. We would have one parent - and any older kids at that moment - able to go back out. But otherwise, we found ourselves back in our room around 5/6 most days. I've seen kids sleeping in strollers so I know they exist. I've heard of kids who nap when you go back to the room and presuming it's not an urban legend. It just wasn't my kids - even when they were babies.
Make sure your child is used to the stroller. When my youngest was 2.5 years old, we figured he would use the stroller at Disney. He wasn't a stroller kid but none of my kids used the stroller when they were little. The older two did use the stroller sometimes while at Disney when they were 3 so I expected the same of the third. He refused. He refused to sit in the stroller AND he refused to walk. Luckily, I had a sling with me and I could carry him that way. He hadn't used the sling for about a year so I wasn't used to it and it wasn't easy - but I had no other option. Before our next trip, when he was 3.5 years old, I worked on this. I bribed him. Bribing didn't work at 2.5 years old. But this time, we did some practice walks with him in the stroller eating candy. It worked. Don't underestimate the power of sugar. (On that note, some carefully timed m&m's worked wonders when my eldest went at 3 years old. You don't always have time to stand in a line - have something to hand over ASAP).
I'm not sure if your child is potty trained, but if so, keep in mind that most of the toilets are automatic. That scared my two youngest for quite a while. We took post-it notes with us to put over the sensors in the bathrooms. My daughter was still used the post-it notes for the sensors at 9 years old. (She did skip using them at 10 though).
If you go to fireworks show, come prepared if you have a sensitive kid. We have to take noise cancelling headphones for my youngest. He's 7 and we still can't go to the fireworks unless he has these.
