In 2003, Kelly Willis and Bruce Robison, two married country music singer-songwriters who you may remember as stars in Claritin commercials from a few years ago, released Happy Holidays, a cover album of Christmas songs. They're still a caroling couple, now they're just doing it live. Tonight, Sunday, Dec. 12, at 7:30 p.m. The Birchmere, 3701 Mt. Vernon Ave., Alexandria. Tickets are $29.50. Call 703-549-7500 or visit birchmere.com.