Calendar Systems:
Paper
Jesse Itzler's giant paper calendar
Brendon Burchard's High Performance Planner
Michael Hyatt's Full Focus Planner
Digital
We literally use our iPhones and share a calendar for our family. We keep our individual calendars as well, but anything that affects our family goes on the shared calendar.
Hybrid
Use both if you want to! Get the best features from both worlds; we utilize paper a lot during our day (post-its, notepads for Top 3, brain dump lists, etc.) but we know people who successfully utilize both a paper planner/calendar alongside their digital version. Also, this can be seasonal adjustments.
The best calendar for you is the one that actually gets used.
