Many years ago I drove through a snowstorm in D.C. with my father to attend the Messiah Sing-Along at the Kennedy Center. I remember that we almost didn't go because the weather was so bad, but I'm so glad we braved the blizzard to experience it.
If you're not familiar with the piece of music, "The Messiah" is a three-part oratio composed in 1741 by George Frideric Handel (the most famous part is the Hallelujah Chorus, which concludes part two). Yes, it is a piece of music about the life of Christ, but many people I know who love it aren't particularly religious. The beauty of the work and the sound of all those voices singing together transcends its meaning somehow.
The Kennedy Center performs the piece as many places do, with four soloists, a choir and an orchestra. But at their Sing-Along, the audience also joins in with the choir. The crowd is so much fun to watch. Die-hards bring their well-worn song books and singing groups often attend together, getting really excited when it's time for their favorite sections and belting out the notes with unbridled enthusiasm (helpful if you need some cues to help follow along). The President even attended the year I went.
The 2014 performance takes place at 8pm on December 23rd. Tickets are free, and are distributed the day of beginning at 6pm at the Hall of Nations, two per person (note: it's very popular, so be sure to arrive early).