Any day that has significant meaning or value to you could be a personal holiday: Your anniversary with your significant other, Mardi Gras, an anniversary of some outstanding achievement, a day filled with personal happy memories (or mourning), a day you and your buddies annually like to have dinner & drinks....you get the idea. Ony YOU can decide what constitutes a "holiday" for you.
but what would you do for an "Easter" break off of work or school if anything in particular?
Anything you want! Sleep late, work on some creative endeavors, go to the gym, spend time with loved ones, go to a shooting range, watch movies, read a book, go to the beach....anything you like. Of course, Satanists could care less about the xtian meanings behind "easter", but Satanists do
welcome things like time off and extra holiday pay!
Moreover, what I'm really getting at is that Satanists don't necessarily stay home and have "dark rituals" on their chosen holidays...but if they do
choose to, that's fine also.
However, if you're looking for a textbook answer, see the chapter "Religious Holidays" in The Satanic Bible.
Better still, feel free to give THIS