I don't particularly like Halloween and since most of the cards specifically say "Happy Halloween," I ended up picking the card that has a ghost on the front, saying, "Boo!" Then, I put a picture of my baby girl on the inside and said, "Just saying 'Hi' in our own special way!" That way it can be a seasonal card, but not overly Halloween-esque. Don't know if that helps you in anyway, but I thought I'd just share what I did in case you're in the same boat.
Thanks, For the Mommas!