In my years of traveling, I have seen a lot of beaches, yet my love for them has not waned. Beaches evoke escape and serenity and romance and childhood’s happiest moments—so many things of beauty, but they can also disappoint with crowds or overdevelopment. I have been lucky enough to sample beaches on six continents, and as everyone does, I have my favorites that I return to and also the blow-me-away ones that I probably won’t see again but will never forget. I was recently asked to name a doze...