WASHINGTON — Nix the flags and the podium. Cue the opulent 18-foot tower of gold-bottled French champagne. When President Obama addresses an elite roster of hipsters and multimillionaires, including hosts Beyoncé and Jay-Z, in New York tonight, he will do so next to a custom-designed tower of $800-per-bottle champagne that dominates the main room at Jay-Z’s 40/40 nightclub. The 350-bottle champagne tower — designed by Jeffrey Beers — is a monument to Jay-Z’s favorite bubbly, Armand de Brignac, which is known colloquially by rappers, clubgoers and connoisseurs as Ace of Spades because of its gold-spade label. “It’s floor-to-ceiling gold bottles...