Another vote for pull-ups here, too. We've been done with potty training for about a year or so, but my 4.5 year old will for sure be wearing a Huggies pull-on diaper pant (he pees way so much a pull-up wouldn't hold him) our entire upcoming visit. He's the type of kid who could use the bathroom and then 20 minutes later need to urgently go again, and he waits until the absolute last minute to pee or poop. Couple that with the excitement and distraction, and the fact that he freaks out from the noise of all the flushing toilets and hand dryers and tries to run from the bathrooms, lol --well, it saved us many times on our last trip about 6 months ago--on a bus, on a monorail, in a line for an attraction where by the time we would have gotten out of line and to a bathroom he would have already had an accident. Even once on It's a Small World, where he needed to poop RIGHT THEN. I couldn't imagine leaving a puddle or mess for cast members or fellow guests, and this was/is just way easier.
Even though I think he probably took advantage a little and may have used the pull-ups as a bit of a crutch, it was so easy to change him if there was an accident (bathrooms are literally everywhere, not to mention the awesome babycare centers) and quickly move on. And he went back to using the potty at home fine, without issue.