I remember reading a study that the plateau for "happiness" that you receive from your paycheck occurs at 75k per person assuming no debt. That would be 150k for a couple. That seems reasonable as a point where you can feel secure in being able to maintain a comfortable lifestyle indefinitely (aka have kids, retire, and still live and entertain yourself).
Well..wouldn't that number be 300k for a family of four then? Unless the people being counted are only those that generate income.