It's funny; I use to complain about the "political correcting" of holidays (e.g., schools no longer have 'Christmas Break' but instead 'Winter Vacation' or some other PC name). But I find myself doing what
cosmocrazy said with my customers; I'll say 'Merry Christmas' to people who I know celebrate it, or at least I suspect of celebrating it (or have said it to me first)--but there's been some people that I suspect
don't celebrate it, or generally don't seem in a cheery holiday-mood, so I find myself saying "Happy hollidays".
But I agree, you shouldn't be
offended if someone says "Merry Christmas" and you don't celebrate it. I wouldn't be offended if I was offered a "Happy Hanukkah". I'd be caught off-gaurd as it's not the normal assumption people make. But personally, I'm glad to have as many "happy" days as I can get.
Then again, there's
a lot of things people get offended over that I think are completely ridiculous. What do I know? :-P