In preparing my marketing plan, there are two things I absolutely, positively can't live without: a large 2×3' year-at-a-glance write on wall calendar and a 22×17" month-at-a-glance desk calendar.
I purchase both from Staples for a total of around $30 and use them together to plan out my year, month, week and day.
The wall calendar is full of "colored yard sale sticky circles" (yep. . .it's a technical term!) designating planned vacations (note the plural), conferences/workshops, my group programs, holidays, etc. – a different color for each so I can see "at a glance" what I'll be doing.
Once those are in place (and also on my desk calendar), I plot out the monthly, weekly and daily activities a month at a time, except for product launches which typically span more than one month on my desk calendar.
You'd be amazed at how this helps to chunk things down so it becomes manageable.
You can get your calendars and "colored yard sale sticky circles" here.