Our opinion of death penalty is shaped by our lives, no question.
Just as the experience of the killer himself lead him to horrible end.
Since we cannot undead the dead and undo the harm done to the psyche of violent criminals, through more death, and more enforcement in general, I'd rather concentrate on why would someone kill? Why is the US such a violent place when other places with similar profiles and not death penalty and a lot less prisons and police, are not.
How different a society the US would be if for example, drug law enforcement money at all levels (prison, courts, police, etc) were redirected into education and support to the poorest.
I'd rather focus on not having murders/rapes/assaults through a more global solution than satisfying our visceral urge for punishment and revenge.