Warning: objects in calendar are closer than they appear.
I can never keep track of the day of the month, it seems. The watch on my wrist has a day marker, but it wants to have a 31 day month, and when we have 30 or 28 day months the day has to be manually adjusted. On the other hand, I have a keen sense for what day of the week it is.
The calendar for me is the ISO 8601 date format that supports calendaring by day of week and week of the year. Today is 2017-W03-5, which is conveniently and readily read as the Friday (5) of the third week of 2017. There are rules from ISO 8601 about when to start the year and what to do when weeks cross year boundaries, but other than that small confusion it’s a very straightforward calendar to use.
The biggest bonus of it is just how readily you can plan for events months in the future, because rather than thinking by month and having to compute odd distances, you can think by weeks and simply subtract.