Years ago my 3 year old refused to go the bathroom for more than 7 hours at Disney World because the automatic flushing toilet terrified her. Eventually a seasoned Mom suggested I put my purse in front of the toilet sensor to keep it from triggering the flush and that did the trick!
The other good trip I remember is to being zip lock bags to hold partially eaten meals. Especially on vacation, kids are often too excited to sit for a meal so they leave too much food behind and then are hungry a couple hours later.
Here is some other good advice we found: