I use normal everyday shoes and not SPD or something similar. I once met a guy who toured with those modern clogs.OK, but I know of a guy who would run marathons in combat boots. I guess it worked for him but most of us used something we found worked better.
I clock around 125 mi pr day.
My problem is that I have used two different SPD shoes when touring. A Specialized MTB shoe and a soft touring shoe both with SPD setup. Both shoes fit perfectly and a are very comfortable when walking around. They are also very comfortable when biking and not too large and too small. However, when touring, my big toe starts sleeping (feeling numb) after 6h of biking or so. It is so annoying that I step out of the SPD system and start using the other platform side of the pedal ... still with the same SPD shoes. And the problem is gone. My feet just dont like to be fixed in one position.