Halloween Day: the fam' and I sit around watching a horror movie marathon usually of my design.
Halloween evening: with a curfew in our town on Halloween night, we dress up (yeah, I'm 35 and still dress up for Halloween, 'cuz I'm that big a dork) and take the niece and nephews out for trick-or-treating. Afterwards, before we let them touch a single piece of candy, we check everything in their bags to make sure it's not been tampered with. Any loosely wrapped piece of candy or anything with a hole is tossed.
Halloween night: each year we take turns to see who will watch the kids while the rest of us go to my cousin's house for a Halloween party, in full costume. It's my younger sister's turn this year.
Tons o' fun for everyone.