I've played a household of ghosts on a few of my games. (If my avatar wasn't a giveaway.) In my plot, the ghosts' attitudes are usually that the afterlife is pretty fun and they'll go out of their way to "help" the living join them. (Usually by trying to talk them into wishing on the Wishing Well when it's in a deadly mood... though my comedian ghost who died by laughter likes to take out Sims the same way she went.)
I wrapped the Goths' story up with the ghosts once as well. Basically, they are the ghosts' guardians, assigned to keep them out of trouble. Cassandra Goth got a ghost boyfriend and child from the Wishing Well, too. She decided she was perfectly happy with this arrangement.
At one point, I went extra creepy and rather than give the ghosts beds, they each got a coffin to sleep in outside in front of their gravestones.
I do tend to cheat enough aspiration points to take away their need to eat, shower, and use the bathroom, because those just seem silly. I can see ghosts wanting to rest, though, even if they don't get physically tired.
If I only have three supernatural states to play, I'm going to use each one as much as I can. ^_^