I've made recommendations in past posts: M/M Romances, M/M Scrooge Romances, Santa Romances. Here are some more from two genres:
Murder Mysteries
Envious Casca by Georgette Heyer: English manor house, Christmas party, dastardly deeds, murder with a history clue, and very dry humor.
Hercule Poirot's Christmas by Agatha Christie: the movie isn't bad but the book--in this case--is better. Christie excels at pithy characterizations. This novel is one of the first Christies I read, and I was completely captivated!
Yes, there are romances in both these mysteries! As for the genre itself--
Romance
Christmas Eve at Friday Harbor by Lisa Kleypas: The first book in the Friday Harbor series, one of Kleypas's best. The book is short, which sometimes hurts a romance (they fell in love how fast?) but works in this case. The book has been made into a TV movie, which I haven't seen, but I can see why it attracted a scriptwriter: meetings in toy shops, meetings on ferries, meetings in the market.
Fortunate Blizzard by L.C. Chase: One of my favorite M/M romances. It combines the tropes of an unexpected encounter (trapped in a hotel during a blizzard) and homemade Christmas with the addition of a problem that pays off satisfactorily at the end (resolved in time for the holidays but not too quickly or unrealistically).