Years ago, a co-worker of mine was flying into CLE on a CO MD-80, sitting in a window seat in coach on the 3-seat side. There was noone in the middle seat. The guy on the aisle "fell asleep" about halfway into the flight. He "slept" through the landing and right up to the gate. It was only then, when the co-worker tried to get up, that he noticedthe guy wasn't asleep, but dead.
He sat there in the window seat next to the dead guy for almost an hour while the authorities went about the process of being notified and removing the body. He just didn't feel right climing over a dead body.
Personally, I would have climbed right over the seat in front of me.