A couple of good free play scripts for Christmas are:
"Ebony Scrooge" (a modern Christmas Carol) - http://freedrama.net/ebony.html
This version even has a female lead Scrooge character. Why should guys have all the fun playing iconic characters?
A great children's play that can be done as a musical is "Songs of the Pioneers" which as an old frontier theme that can be done as a holiday play. It's a good script for celebrating winter holidays in general. http://www.freedrama.net/songs.htm
And another good children's play is "The Star" which would be great for a church group: http://freedrama.net/star.html
"The Star" has fun animal characters that child actors (and adults) would have fun playing but has a good theme about the true meaning of Christmas.