Had a story idea yesterday that I don't know if it's been explored before, but I could see some interesting outcomes from.

A couple die in their house. Don't realize they are dead. They continue their "lives" in a ghost world, completely unaware of that fact.

But they are constantly dealing with the fact that their house is "haunted" by the living. Who are also freaked out by the fact their house in haunted.

No real animosity toward the other side (so not Beetlejuice), just coexistence.