After much thought I've gone for Gandalf. I toyed with the Hobbits, all of whom I think would make marvellous Christmas companions. And also with Elrond - also think Rivendell would be a fantastic place to spend Christmas and he does have the biggest fire! But in the end Gandalf won me over.
He can be very merry company when he wants and he has fireworks

. I would expect several of his best ones. He wouldn't have any trouble lighting the fire and after dinner (I'm sure he's a good cook) he can tell tales of all his travels around Middle-earth. But I'd have to put up with all that pipe smoke!
Maybe I can persuade Gandalf to spend Christmas at Rivendell

.
Now - a present. Maybe a pair of very comfy slippers for his tired feet and a lifetime pass to the Library at Minas Tirith with unlimited borrowing rights, his own chair and exemptions from overdue fines.