I am definitely not a regular flip-flop wearer. I have very bad feet and absolutely no cartilage in one foot (due to a very bad hiking injury). So, if I can do it at WDW, anyone can. A few years back, I was in the Rain Forest Cafe shop and noticed some pretty comfy looking flips. They were black and had tire tread marks on the bottom. Tried them on and they were super comfy. I ended up wearing them for a full day in AK and had no problems. The following trip, I purchased a really great brown pair that were even more comfortable.
I've become so hooked on these that I made an extra trip to AK last trip just to check if the RFC there had any left (DTD was sold out). They had them and I bought pairs for all my friends and family. They are standard issue WDW gear now. Try 'em, you won't regret it!