“Winemakers tend to put their best bottlings—tête de cuvée, they call them—and the best vintages, wines they’re really truly proud of, they’ll put into a large format,” says Joe Robitaille, head sommelier at Bar Boulud in New York City, where he opens one large-format bottle each night to pour by the glass. “And the reason they do that, it’s a little bit of a time-capsule effect because the wine will age much more slowly and much more gracefully inside of the really thick glass of the large bottle.”