Buying summer footwear that is cool and comfortable doesn't have to be a battle or a guessing game. More and more manufacturers are recognizing that people want the comfort of cool sandals while at the same time keeping their feet secure and well supported. Look for sandals and flip flops that have a substantial sole on them so that your foot is well insulated from the ground. It you can't find a thick enough sole at least choose sandals that have a very small heel. Heels will add to you discomfort, especially if you're walking and touring.
Leather is a good choice of material for your sandals, since leather will let your feet breathe and will also be pliable and comfortable. Although you may be spending a bit more for leather sandals the additional expense will pay off in the long run. When it comes to flip flops, they are great for taking on vacation and wearing around the pool or at the beach, but when it comes to walking you're going to want to stick to sturdy leather sandals.