I would second (third?) Birks, with a *glaring* notice to make sure they are properly broken in. I wore a pair of Yaras that I *thought* were sufficiently broken in on the first day of our last trip. By the time I was through two airports and to the back of World Showcase, I had tears in my plantar fascia, and most of the skin around my ankles had been rubbed off. The rest of that trip was completely miserable, and two years later, I'm STILL having problems with plantar fasciitis. For the record, I've never had that problem with any other Birk style I've owned, so maybe that style (for distance walking) was just all wrong for me.
We're heading back in May, and my list so far includes Danskos (Not just clogs, anymore! I can vouch specifically for the Hazels, as far as the more sporty/athletic but still cute styles go. I can be on my feet for 10+ hours a day in those and the comfort is pretty comparable to my Pro clogs.) Keens, a pair of Asics sneakers, and surprisingly, a pair of Crocs Capri IV flip flops that are the ONLY thing I can put on my feet when I first roll out of bed in the morning.
I'm excited to look into Merrells, Chacos, and Vionics, as well!! Thanks for those suggestions!