Most of our traditions do involve the kids, but we have a few of our own:

Making turkey sandwiches for Santa. Watching "Die Hard' while sharing a bottle of wine and wrapping gifts. . . . and eating turkey sandwiches.

Adopting a family or participating in Angel Tree--then shopping and wrapping gifts together.

Listening to my grandmother's Christmas albums on her 1950's record player.

Watching A White Christmas.

We always sit down b/w Christmas and New Year's and plan the races and events we want to do in the coming year. That's always fun and motivating.

A nekkid nap on the afternoon of Christmas Day. Thus thoroughly annoying DH's sisters when we are supremely late for the big In-Law Christmas gathering. lol.

Run the New Year's Day run together.