As if Italy’s many superlatives — world-class museums, spellbinding archaeological sites, charming small towns, and fabulous food among them — weren’t enough, the country also has some of the most beautiful beaches in the Mediterranean. They’re not exactly well-kept secrets, especially in July and August, when many of the best beaches in Italy are packed elbow-to-elbow with Italians reveling in their annual one or two weeks at il mare. Still, if you know what to expect — or you visit during the shoulder season months of June and September — a beach sojourn in Italy rewards with stunning scenery, impossibly clear, blue waters, and, in many cases, a uniquely Italian…