There's really not much to be said for the calendar, except that there must be One Calendar to Rule Them All. You can use Google, or Outlook, or iCal or a paper solution, but you should only be keeping one master calendar. Otherwise, you invite chaos.
I personally recommend a web-based calendar such as Google's solution, because it allows for cross-device sharing and integration with great services like Doodle . If you are using iOS, I suggest Fantastical , which integrates with the iOS calendar and is the smoothest App I've found so far. On MacOS, I use Fantastical. I haven't used paper in a long time, but when I did, I loved Franklin-Covey . Their binders and fillers kept it interesting.