Adventures in Good Music

I've been geeking out listening to more traditional and even some ancient music. Our church is going to start a new worship service after the beginning of the new year -- a communion service that will be about 30 minutes long. It will have a short homily, a solo piece, a hymn or two and half the time a sung liturgy and half the time a spoken liturgy. Question for those who love music as much as I -- what are some quiet, contempletive yet joyful and celebratory pieces that you personally love? More traditional than contemporary? I love things like "Be Thou My Vision," "Oh Sacred Head Now Wounded," and "Oh What Wonderous Love is This." I also love "Agnus Dei" by Faure. What else do you think could be used?