In Russia, the main winter holiday for most people is New Year (December 31). Religious people also celebrate Christmas (January 7). People working for the state usually have a 10 days holiday from Dec 31 to Dec 10. If you work for a private company they often make you return to work earlier.
Also we have a nice goofy tradition - The Old New Year - a celebration of NY by the old calendar. It's on January 13th. It's not an official holiday and people don't even look at it seriously, but some like to have a little quiet party with good friends or family and that is the 'real' end of the winter holiday season in people's mind. Many people keep their Christmas tree decorated till the Old Ney Year and remove it after that.