Not to anger Linus Van Pelt, but do Christmas shows really need to be about Christmas? I think these days, it's more just about putting on a show at that time of year.
Anyway, I think of "The Blue Carbuncle" as a Christmas story. If they ever do a movie that's a proper adaptation of the short stories, then I'd like it to include this story plus a few others. The movie could have one story in spring, one in summer, one in fall and one in winter. I'd much rather they did that than trying to stretch out one short story for a whole movie or adapt the novellas.
All of the novellas are padded with content which has little of Holmes in it. A STUDY IN SCARLET is a good introduction to the consulting detective, but then it goes on this flashback story and takes a long time before it returns to Holmes and Watson. The other novellas are even worse for this kind of padding. The short stories are where it's at for me.