Keens. I have fallen arches, and they are the only sandals that I have been able to walk in extensively. I have tried Tevas, flip flops, Danskos, Eccos, and Clarks. They don't look like they have much arch support, but they are surprisingly great. I usually have to add arch support to most of my shoes, even nice European walking shoes, but not the Keens. I have hiked WDW twice, DLR once, and multiple miles in Hawaii and around Austin in mine without any problems. I was worried that it wouldn't be warm enough to wear them on our trip last week, but luckily, it was. Mine aren't particularly pretty but neither are sore feet and calves. They have really good traction in the wet too. Mine are a water-rated version, but they don't sell the particular model anymore. They are expensive, but they have lasted a long time. I have had them for over a year and a half, and I wear them almost everyday March-November.