We always do door decorations. Actually, depending on our cabin location, we do hallway decorations, just outside our door.
We are from Ohio, so we do a map of Ohio, with indications of major cities, plus information about those cities. For example, for Columbus, we have "State Capital", and "home of The Ohio State University". Also, an explanation of what a Buckeye is.
Helps us find our cabin when we're coming back late at night. Plus, it's fun to hear the cabin steward ask "what's a Bookie?"