sleeping in!
Oh yea! It's tough to pull yourself out of bed when your technically on vacation. There are some days we don't get to the parks till 1130am. Got to work on that this year.
Trying to push your group too hard. Many seem to push their kids to the point of meltdown and then yell and scream at the kids for not "having fun". People don't seem to realize that kids are best when we try to stick as close to their home schedule as possible and realize that all that Disney has to offer can be overwhelming to the little ones.
Not being in good walking shape.