I made Spooky Day holiday with Spooky Spirit, Trick and Treat, Wear Costumes and Decorate. One of those did bring my played ghosts wandering around the neighborhood in the evening/night. At one point there was at least five of them just walking around the neighborhood. They didn't come to the house, but just wandered the usual walkby routes.
Talking to Vlad and his vampire family didn't seem to count for Spooky Spirit, though, which is weird. The most surefire way of getting Spooky Spirit done for me was carving pumpkins.
Trick and Treat seemed to be very time specific, around 6pm and some. My played sims were visiting Vlad at the time and there was one teenager and one child in costumes and Trick-and-Treater tags on them, but when I returned to the home lot in Willow Creek, didn't see more of them the whole holiday.