Totally varies by kid. We found that age SO easy! Our kids would hang out in the stroller, napped there as needed, no end to things for them to do/ride, and spent a good amount of time walking so they took those stroller naps... those were the days we could go rope drop to park close and it was still fun for all of us. We were mostly doing 7-9 day trips back then and would easily spend 4-5 at least partly in the MK.
When they started walking themselves, too big for a stroller around 7-8 and getting tired, crabby, stressed out because they couldn't hide from people... It went downhill until this year when the youngest is basically just a short adult so we really appreciate that we went in those early years.
Then we went with a family who is much more rigid in their habits, kid HAD to nap in the room, in complete silence and be in his physical bed by ~8 PM. Would stroll but dad didn't want to risk them running off so the stroller was treated like a prison. To us it basically killed the day. I bet they are going to think WDW is awesome around 7-8 years old.
So think about who your kid is, and how YOU manage situations with either strolling or walking with you in a crowd when they want out.
OH- and the real tip, seriously, you are who popcorn buckets and those Gogo squeeze type pouches are made for. You are walking an extra 5 miles/day, and so may be your child. You are all hungry even though you "just ate" or dinner is "only an hour away" Yes, healthy snacks are great but at some point you also have to go for "here, stuff this in your face so you can smile again" until you get to the food. Every time someone has started to so much as look like they might not smile we have handed them food and water and it has been a lifesaver.
