I just discovered Vitamin String Quartet. I literally mean, just now, listening to their 3rd or 4th cover.
If you haven't yet, but struggling with choosing ceremony music like I was (yes, not anymore, yay), because you don't want the traditional, but don't really want to "rock the house", Vitamin String Quartet is the way to go.
Just listen to this
http://www.youtube.com/watch?v=wcIX0KTvh8E&playnext=1&list=PL4167AD8BC28A14F4
or this
http://www.youtube.com/watch?v=sGhWRMGHHe8&feature=related
Or search their other songs on youtube: Vitamin String Quartet and the name of your fave band. I tried, and in like 70% they did the cover for my fave song.
I build my entire ceremony on their music. I'm walking down the aisle to Something by The Beatles. It's beautiful!