I was just in McDonald's having lunch (I know, I know) when I heard some woman singing "O Holy Night". It kind of surprised me because you don't often hear religious Christmas carols in the public square any more. The woman was a talented singer, but she just didn't have the pipes for that song.
"O Holy Night" is one of the all-time great solo songs for someone with a really powerful voice. That surging crescendo will shake you to your bones when it is done right. But the melody is too slow and simple to work on its own; it really needs that crescendo. A soloist without the vocal power, even a good one with an interesting voice, should stay away from this song. As a congregational song it can be downright grating.
Another great song for a powerful voice is "It Is Well with My Soul". The crescendo in that song can wring your heart.