I've got a calendar on the wall which works well for an overview of all the family activities going on.
I also use my phone to diarise things mainly so that I can use the reminder thing to pop up & remind me of all the zillions of things I would otherwise forget!
I do miss having a paper diary as I like having an overview in front of me &'adding notes/lists etc. Not sure I could cope with having to update in 3 places though!
What do you use, paper, electronic or both?