I have three MCs (which might be a big surprise to anyone reading the book so far).
Odin is Festivus sort of guy. He's practical He believes that religion and commercialism both have their places, but they should not be mixed. He would erect an aluminum pole in his command ship. He might command his minions to bow before the pole just for his own inner lols. If challenged, he's willing to erect the largest Festivus Pole in the universe.
Shiva is all about the parties. Since New Years is the most intensely packed holiday of the season, he would focus on that. Oh, I know. He would speed around a planet in order to enjoy midnight several times, once per time zone. Then he would travel to another inhabited planet and repeat the process for a two (or three) day long epic bender.
Isis is tougher to pin down. She likes them all. She likes decorations, so she would probably celebrate all of the holidays of the season so that one flows right into another without pause. From the twinkling white and gold of X-Mas to the vibrant colors of Kwanza, her home would be an absolute assault on the senses.
None of these characters have much of an appreciation for restraint.