I grew up in Utah with Mormons ALL around! I never really saw Christmas as a strictly religious holiday. Go figure. At the Mormon gatherings I attended as a kid, I just went along, completely UN-offended, and just enjoyed the parties and gatherings. When group prayers were said I sat quietly and respectfully as they did their thing.
So many things about this season have nothing to do with the birth of Christ anyway.
It really means something different for everyone. Fact is, it's pretty much a national holiday, whether you celebrate or not, whether you observe it as a religious event or not, no one can deny the HUGE impact Christmas has on our economy, our jobs, our schools, our vacations. It's a special time for a lot of people, so why give them grief for it.
I forgot to mention I work with a couple of JW's as well, and they don't celebrate any holidays, even birthdays. They are not offended either. They are adult enough to realize that someone else's celebration isn't an offense to their personal beliefs.