First off it's helpful to know what is at Disney World. There are four theme parks, (Animal
http://disneyworld.disney.go.com/parks
Also remember that if you are hopping from park to park, it's not like at Disneyland where they're right next to each other, you have a bus system to navigate also. Bus rides are generally about thirty minutes between parks.
If you plan on going to Animal Kingdom, go there as early as possible. (If your hotel offers an early bird pass to one park take this one if you can.) As soon as you get there get in line for the safari ride. They really have an amazing variety of animals, but if you wait too late in the day they're all hiding in the shade. This is especially true in the prime summer vacation months.
For some reason that I can not fathom, there isn't a lot of child friendly food available. Where are the kids meals?!?! Magic Kingdom had little hamburgers at one place, but that was it, and if you have picky kids like I do, that's not going to fly. My solution was to pack a couple Lunchables each day and have lunch by eleven, before the cheese gets too warm. I also packed granola bars, fruit snacks, crackers and dried fruit to snack on throughout the day. Also pack water bottles for everyone. Florida water tends to not have the greatest flavor, (some of the truly picky call it poison.) and goodness it gets hot there. The sodas that you get with your meals probably won't be enough.
Renting strollers there is expensive (if I recall it was $30 per day for a double) and if you are going to be there for a week, it is totally worth it to bring your own. (I bought my double stroller at Target.com for $110. It was definitely a good investment.) If you have your kids ride in it up to the gate you won't be charged extra to check it. They'll just tag it and stow it as you board, free of charge. :)
Have fun!
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