I am a Realtor in Upstate NY. I always say Happy Holidays to my customers and clients because I work with mostly people from NYC. However, if I know for sure that someone celebrates Christmas I will say Merry Christmas. I don't say Happy Holidays because someone told me to, I say it out of respect for other people. That being said, and I do celebrate Christmas, I would not be at all offended if someone wished me a Happy something else because if that is the worse thing that ever happened to me, I think I would be doing pretty good.