It Came Upon a Midnight Clear for vocal, keys, strings, flute and percussion.

A classic in a very peaceful setting in the key of G to Ab.  This tranquil arrangement can be used as a vocal solo or singalong.  This will also work with a string quartet or ensemble.  Also, though there are four percussion parts with multiple instruments, you could reduce the number and still achieve the ambience.  Be sure to view the score sample.  This could be performed with light brush drums as the only percussion part. This is very easy to perform with a wonderful calmness in the performance.