Fancy Nancy Splendiforous Christmas by Jane O'Connor is a book any Fancy Nancy fan would enjoy. Nancy loves Christmas, and loves everything that goes with it. I read this to my some of my second and third grade students and they enjoyed it.
Stable in Bethlehem, A Christmas Counting Book by Joy N. Hulme is another great book I came across this year. It is short and counts backwards from 12 to 1, including all the important things about Christmas, like the shepherds, the three kings, and of course, Jesus, Mary, and Joseph. The illustrations are very well done, too. If you are a stickler for accuracy like my dad, you might not like it, though. It mentions dogs (we don't know if they were part of the Christmas story) and gives a number to both shepherds and kings, which we also don't know. It is great for younger children because it is a short story.
A few more books if your children are fans of certain characters:
Merry Christmas, Ollie by Olivier Dunrea
Mrs. Wishy Washy's Christmas by Joy Cowley
Minerva Louise on Christmas Eve by Janet Morgan Stoeke