I always like to be able to see the entire school year at a glance.
I've included here the Excel file. You can edit the colors if you don't like the ones I have. It has two sheets:
Sheet 1: School Year split up by marking periods according to our school in NYC.
Sheet 2: School Year split up by month.
I've highlighted regents weeks, holidays, school breaks, PD days, and parent teacher conference days.