Hi Jennifer,
I'm a flip-flop girl, so I'd love to talk about Disney-worthy shoes! I actually prefer flip-flops and sandals because of chance of rain; I can't imagine walking around in wet tennis shoes, ewwww.
My current favorite flip-flops are made by Crocs, and I have several styles that are all comfortable and stand up to miles walked at WDW. My whole family actually wears Crocs in various styles on all of our trips, so they get 10 thumbs from us. Mickey Crocs are also sold throughout all of WDW, by the way.
I'm also very fond of sandals/flip-flops made by Teva, Merrell, and Keen. As a precaution, I do bring along some band-aids, mole-skin, and a product called Blister Block to use if any of us begin to suspect a beginning blister.
You will be amazed at the shoes people will wear at WDW and wonder how they survive the day; I've even seen high heels at the parks!
Happy walking!!