It can be tricky. I mean, you could talk to the ghosts, but they rarely answer back. One of them tried to make sure I knew how to tidy the kitchen a while back, and there's a little boy that lives either in the library or the room with the pool table who likes to watch any games that go on, but that's been about the height of it.
You could try cooking? The food supplies always seem to restock so there's always fresh ingredients. Or drawing, maybe? I don't know if there's a lot of supplies for that, though.