This past year a former co-worker of mine passed away. I had worked with him for about five years. We were still in touch and had many colleagues in common, I knew his wife and his daughter babysat for us a couple of times, but for the most part our relationship was purely professional. He was just a genuinely nice guy whose family didn't deserve to have this rotten thing happen to them. When he became ill his family made it known that they wanted privacy. I attended his funeral as did all of his colleagues.
In past years my family has sent his a holiday card and of course they are still on our list.
I was thinking about foregoing the chatty holiday letter I'm sending to everyone else this year and sending them a nice card with a personal note. I don't want to be too personal but I'd like to do something they'd appreciate. Does anyone have any suggestions on how they would approach this without being too impersonal but without going overboard on the sentiment?