In my eyes, I guess it depends on how much you plan to do in a day. Our first trip with my dd she was 5, and we definitely had a stroller, her next trip she was 7, we still had one, because we knew we would be in the parks longer then she would be able to keep up with. This way she could relax and not necessarily slow us down. Also it depends on the child. Our DD is (and was) a smaller girl in height. She cannot walk as fast and gets tired quicker compared to me. To her credit though, we were out until almost 1 AM yesterday and she pushed through. She did, however collapse, when she finally hit the bed at almost 130 AM. She was a bit of a bear at 715 AM when we woke her to go to O'hana (She is a "Stitch" Nut though).
Point is, I think at 7, it's a nice precaution, because, pampered and catered or not, a whiny child (and worse, a whiny adult) makes for a miserable vacation for everyone involved.
The Trip where our DD was 7, was her last trip with the sttoller though.