What do you really need to pack for Disney World?

With so many packing lists out there, how do you decide what you really need to pack for a Disney vacation?  We've vacationed at Disney World 5 times now so I feel that I'm justified in calling myself a semi-expert.  Here's the thing - Disney is not in some remote location.  There are stores everywhere and you can pretty much buy anything you need.  But if you bring certain items with you, you'll save money and time.    

So what do you REALLY need?

Two pairs of comfortable shoes for each person
  When packing for vacation, I follow the 3 pairs of shoes rule.  This rule states that any person should not need more than 3 pairs of shoes during a vacation.  So, for Disney, I used to pack a pair of sneakers, a pair of sandals and a pair of flip flops.  The sneakers were obviously for wearing to the parks.  I would wear the flip flops to the pool, and the sandals around the resort.  During our 4th trip, it poured rain all day, every day but one.  My sneakers were sopping wet despite trying to dry them with a hairdryer so I decided to wear my flip flops to the park.  Big mistake.  It was the end of September and I had been comfortably wearing flip flops all summer.  My feet will be fine.  I learned the hard way that there's a big difference between wearing flip flops all summer and spending an entire day walking 8 miles in flip flops.

You may get lucky and not see any rain during your vacation, but this is Florida and you'll be spending a good deal of time outside.  I would plan on rain at some point.  That being said, you can avoid the whole wet shoe issue by packing 2 pairs of comfortable walking shoes for each person.  Don't forgot about the kids.  They need to be comfortable too.  When I say "pack" here, I don't mean bring extra shoes to the parks with you.  Leave them in your hotel room.

I also would not suggest buying new shoes for Disney.  You're going to want them to be broken in before you spend the day walking 8 miles in them.

Rain ponchos
  Yes, you can easily purchase rain ponchos in any Disney store in a park or a resort but it will cost you more money.  Also, once it starts raining, it's much more convenient to actually have the ponchos on hand.  If the forecast doesn't show rain, we leave these in the resort room.  Unless it's that time of year when it seems to rain almost every single day.

Sunglasses and sunscreen
  Convenience and cost.

Water bottles/sippy cups
  Yes, you can bring your own food into the parks.  (No glass or coolers, except for small, soft ones.)

When the girls were really little, we brought empty sippy cups with us to the parks.  They are big milk drinkers but the parks sell these large containers of milk at the quick service restaurants.  By having our own sippy cups on hand, we could easily split up the milk.

Buying bottles of water can quickly add up.  Did you know you can ask for free tap water at quick service restaurants?  
 
Snacks
  Because kids need to eat approximately every 90 minutes.

Rain cover for stroller
  If you're using a stroller, it helps to have something to keep the stroller seats from getting wet in the rain.  Most stroller parking is uncovered so if there is rain, expect wet strollers.  A large garbage bag helps.  Or you can place a smaller plastic bag on the seat if it's wet.

Phone chargers
  I've never actually needed to charge my phone at the parks.  When we're there, I really only use my phone for reservations and to check wait times.  I know this is not the norm though.  If you do rely on portable chargers, check out FuelRods.  (Google it - I've never used it so I can't comment.)  It may be more expensive than bringing your own but some park-goers rave about it.

Other/Personal
  Obviously, we all have other items we feel are necessary but I find those vary by person.  Hand sanitizer? Autograph books and pen? Camera equipment?  Two of my personal must haves are hand lotion and lip balm.  Every bag I own is stocked with both.  Keep in mind for the above list that I tend to be a light packer.  I know some people bring anything and everything they could possibly need.  My goal is to keep those bags light.