If your little one is tired (I'm talking the 3 and 4 year old range) AND will consent, PLEASE get them a stroller. The only thing worse than navigating through strollers, is tripping over a toddler who has fallen asleep walking. And yes, I've seen it. My own father wouldn't get my sister a stroller, and she did fall asleep walking. Do it for the kid's sake, and for those around you. And trust me, I have the most persistant sister around, so I know that not all will consent to being in a stroller. But try.
If you're throwing up, leave the park. I've seen people throw up, then keep going. Saw them later in the day, puking again. Sorry, I don't want to see it, or catch it. Yeah, this is your vacation but wouldn't you enjoy it more if you got better faster, or didn't puke all over those nice new vacation sneakers?
And don't try giving nasty looks at people with a gross cough. If they look sick, yeah they shouldn't be there, but not everyone in this world coughs only when they're sick. I'm not a smoker, but I have that nasty smokers cough 365 days a year. When I'm sick, you'll know it. But even when I'm not sick I still hack. I cover my mouth, and aim away from people, but that's about the best I can do. Don't give me a hard time about coughing. It's happened many times, and there's nothing I can do about it.
Have to echo the comments about the toilet seats. To quote someone last year on this board, "If you must hover and spray, wipe it away".
In the parking lots, when they say everyone behind the line so the tram can leave, get behind the line. 9 times out of 10 there's another one waiting right behind the one that's full.