Now this is our kind of happy hour: sipping bubbly in the Dom Perignon lounge, grooving to a house DJ, and nibbling small plates like zingy lamb meatballs and spicy clam-and-pancetta pizza. At this new Financial District fixture (which replaced the Langham Hotel's old restaurant, Julien), the after-work crowd, tourists, and late-night revelers mingle over martinis into the wee hours.