When I was about that age, I would have enjoyed coming up with some ideas of my own. Maybe have a day that say's, "think of something fun to do for someone else."
He might choose to buy a toy for a kid, bake cookies for a neighbor, take a gingerbread house to an old lady, or any number of things. Coming up with ideas is part of the fun IMO.
This advent idea is a good one. We always had the cardboard ones with chocolate when I was growing up. Maybe I will start doing it this way for my kids.