I would say the big one to start is Family Traditions, and the like. Ideas:
A weekly or bi-weekly date night where you go do something different (no dinner-and-a-movie.)
If you don't usually have a "Family Dinner", make one day of the week a "Family Dinner" night.
Weekly or monthly get-together where you can hash out plans, see what's been problematic, hopefully correct things before they lead to arguments, etc
The yearly traditions such as: having a jar where you write down all the awesome things that happened on slips of paper, and read the paper on New Years, various holiday traditions, or yearly vacations, or whatnot
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.