One thing I'd like to share is that, according to Philodemus's On Piety, Epicurus enthusiastically took part in the festivals and rites of Athens. He may have had his own internal interpretation of them, but he didn't shy away from celebrating them.
I think that's a valuable lesson. We can take part wholeheartedly in traditional - even religious - celebrations of the season as long as we remember to leave the supernatural trappings behind - even if it's just by keeping it to ourselves.
If you enjoy carols or even the pomp and circumstance of a midnight mass or church service, go for it unreservedly.
We have an exemplar of our own in the "master architect of happiness" himself.