Admittedly we have a complicated set of issues when it comes to holiday cards - we have Agnostic, Atheist, Buddhist, Christian, Jewish and Pagan friends and relatives (and that is just the alphabetical list off the top of my head!) all in various states of touchiness and often in the same household. But we like to send out cards because we (OK, fine, I) like to show off how cute our kids are. (They really are totally freaking adorable! Seriously.) But so do most Americans in the 21st century.
So I send out about 200 cards every year, and my normal note on the bottom of each card (since I'm not fond of stamped out cards with no handwritten touch) goes something along the lines of, "wishing you a happy holiday season and a wonderful new year." If I know for sure the whole family is Christian I might say "Merry Christmas" instead of "happy holiday season" except in those cases, where I know the recipients are way on-board the "persecuted Christians you have to say Christmas and can't celebrate any other holidays in December, I can't hear you unless you only mention MY holiday, la-la-la" bandwagon.
You know the type I mean. The ones that send out cards that say "Remember Jesus is THE reason for the season" (maybe your reason, but certainly not mine) and put on bumper stickers like "It's OK to say Merry Christmas to me!" (are they really worried people are dying to say "Merry Christmas" but are scared to because Christians are such a small percentage of the population and non-Christians get so offended they might hit them with sticks for mentioning their holiday? - I don't think so.)
Now for those people, I take perverse pride in writing a generic happy holidays note, and especially in knowing they are seething, but can't yell at me because I grew up Jewish and then they'd just sound like assholes for being mad that I am wishing them happiness. Which they are. OK, maybe assholes is a little sharp. How about self-absorbed babies who can only count their own religion as valid and want to make everyone celebrate theirs. Don't believe me? On Dec. 20th this year, when one of these types (look for the bumper sticker) says "Merry Christmas" to you, answer "Happy Hanukkah" or "Blessed Yule" (I don't care,whatever floats your boat) and watch what you get back from them. (I happen to personally enjoy confused sputtering.)
Now it will actually be Hanukkah and Yule and not Christmas on that day, but that won't matter to the Christmas bullies. They want to own the whole month of December. I feel badly for trolling them, but then again - they started it. To be fair, I also send purely secular cards that might have pictures of trees, ornaments and/or reindeer to my crazy "I can't believe she married goyim" relatives as well, because I know it makes them crazy.
Yankee Swaps - fully grown adults literally taking candy from children - really? Who decided that taking a present away from someone was a fun game? I'm declaring myself allergic.