The kind of thinking I'm talking about isn't about choosing one option, regardless -- "no matter what, I will only die at home with my family, with no drugs whatsoever" is one of those things that might sound nice for a moment but is a horrible option for some situations.

Instead, I think it's important to research the main philosophical approaches to end-of-life, to find out what the major decisions are (and what people tend to do, and what people tend to regret doing...), and just know what the options likely will be.

Simply asking the practical question "what will my life probably be like, and for how long, if we attempt this treatment, vs if we don't?" is something you need to know how to ask.

Another big one that you do need to decide in advance to avoid all kinds of potential problems: what guidelines should my loved ones follow when making decisions for me, if I'm comatose, seriously brain-damaged, etc.? Some people end up being kept alive for years in a hospital bed, even brain-dead with no chance of recovery, at huge expense, because they never thought to tell their loved ones "I wouldn't want that", and without that no one feels morally freed to pull the plug.

If they can't say "it's what s/he explicitly instructed us to do", they may well feel morally trapped into doing anything medically possible to keep you alive (even with no hope of recovery), because otherwise it looks like they're doing what's easiest/cheapest for them.