Lady Antebellum, the trio of Hillary Scott, Charles Kelley and Dave Haywood, is famous for its pitch-perfect harmony, which began when they met in a Nashville bar 12 years ago. In this week’s “Sunday Sitdown,” Willie Geist got together with the band to talk about that first meeting, the Grammy-winning song that changed their career, and how they manage to stick together after all these years. Plus the band took Willie on a tour of their rehearsal space as they get ready to head out on the “Summer Plays On” tour with Darius Rucker.