My podiatrist insisted I get arch support in a sandal due to sports injuries. Fitflop was one of several lines she suggested. The others either hurt (Orthaheel) or were slightly less comfortable and even more informal than the Fitflops (Skechers Tone-ups).

Although they still seem clunky to me compared to nicer sandals, say Coach, they are way comfortable. You can dress them up or down, which works in California where folks where flip flops practically year round. My only reservations are the photo the sandal looks taupe, which I would have loved, while real deal is pure pewter, and they are way pricey.  You can't beat the comfort, however; the upside of the thick sole is they add an inch or so of height. Reasonable compromise if you have foot damage.