Grazie Mille, 1100 15th St., NW. Grazie Nonna, which rode the Italian-American nostalgia wave when it opened last year, now has a showier cocktail bar neighbor. Grazie Mille, sticking to owner Casey Patten’s gratitude-expressing naming scheme (his downtown sandwich shop is called Grazie Grazie), opened for drinks, Italian bites, and live-spun music last week. With