I feel that the airline is responsible. Ex's mother is a flight attendant for US Airways, and the numerous times I have flown when she was on duty, she has awakened passengers, its their job. They are supposed to clear the aircraft and make sure no one is in the bathroom, and that no one is in the galleys. In this case, the woman could have been dead or passed out. This is neglegence on the airlines part.
BUT, this is not lawsuit worthy in my opinion. I think that people are so lawsuit happy, that they are looking for any reason to sure to make some money. Though the airline personnel could have woke her up, what was the harm in her setting her alarm clock so she could wake up when the plane landed? I mean from DC to Philly is like a 20 minute flight... (I flew from Richmond to Philly, and was only in the air 30 minutes) How much of a deep sleep could she have been in?
I say if they offer you a lifetime supply of flyer miles then take it... Goodness, what dollar amount could she possibly get for this?