In my own classroom, I often like to have music playing in the background. I start it as we dismiss from circle (if we have one first thing in the morning), or simply put it on at the request of my students.
If you don't have a CD on hand, you can play this Enya compilation from YouTube. It consists of her "greatest hits" and only shows the album cover for the video. It makes for excellent background music.
My favorite song is definitely "Only Time." It often moves me to tears. "Carribean Blue," "Book of Days" are other favorites. Which track is your favorite?