I quickly learned during my first visit to Walt Disney World as an adult that footwear is everything when it comes to all-day comfort, and those stylish but flat sandals do not cut it.
My feet actually burned in pain after spending 12 hours our first day walking from one side of Magic Kingdom to the other and back in an extremely cute pair of sandals that had zero support.
Honestly, walking in those shoes all day was the equivalent of walking barefoot on concrete. If I had to take one more step in those, I probably would have laid down on the sidewalk and pitched a hissy fit that could put a tired and hungry two-year-old to shame.
That was the first and only time I made that mistake.
Nothing ruins a day in your favorite park quicker than painful feet. You are going spend several hours each day in whatever shoes you choose as you navigate parks (I average about 30,000 steps each day at WDW), so it is important to be thoughtful in regards to footwear.