I have plantar fasciitis, so have to be careful which flip flops I wear. My favorites are OluKai Ohana (warning though they do have fairly high arches). I also like the Cobian braided Bounce, Sketcher Tone Up Glam Punks (don't care for the other Tone ups though--too tight on top of foot), Orthoheel Tides and Waves, Fit Flops, and Montrail Molokinis. I got a pair of Cobian Braided Bounce a few days ago, took them out of the box the next morning, and walked my dog two miles and they were wonderful--didn't bother between my toes and felt like heaven on the soles of my feet. They do run a size small though.
I used to swear by Teva Mush (the Originals not the new Teva Mush 2's), Yellow Box, Reefs, Nike Celso, and Yoga Mats, but can't wear those much anymore with my PF.