The Dean-or-another-person instances I'm thinking of are 'In My Time of Dying' (obviously) and the two from 'Faith' (all right, so only one actually dies in-episode, but it amounts to the same thing). In 'Scarecrow', Dean and the girl are tied up as the sacrifice, but because they're freed the scarecrow takes the aunt and uncle in their place. In 'Nightmare', Dean is supposed to die, but Sam intervenes and Max shoots himself instead. (Obviously, Dean's going to feel less guilty about the 'Scarecrow' and 'Nightmare' deaths, because they were all people who were trying to kill him, but still, for Dean be alive a lot of people have had to die.)

There was also Dean being tired, and not thinking he was allowed to stop otherwise.

Oh, yes. 'Croatoan' made it so painfully clear that Sam is the only reason Dean is keeping himself alive.

AND BOBBY IS AMAZING AND I HATE MYSELF FOR EVEN CONSIDERING HIS DEATH, AUGH.