Might I suggest a wonderful book/movie I saw that comes to mind with this topic? "Tuesdays with Morrie"....I saw the movie, and I cried through the whole thing, it was so powerful!! The old man was painfully dying, but remained mentally strong, and before he left, he completely turned a young man's life around, and gave him some powerfully enlightening teachings during his last days. Please see this movie if you can!
My personal opinion, follows this book. I would rather spend my last days, in the comforts of my own home, with pain meds if need be. Until our last breath is drawn though, should we use each day to it's fullest potential? Maybe share one last story with our youth, or try to touch one last person before we go? As Temptress said, when it's our time, in God's will, we will breathe our last breath. Without the help of modern technology etc. I like to use the "oldtimers" as an example. Back then, they died in their homes, sometimes after a long battle with sickness etc. but they died with their family around them, and peacefully I'm sure, with dignity...? I'm just guessing, I'm only 27. That to me, sounds better than having my body look like a pincushion from all the tubes and wires and needles in me. I say, use every last day to it's fullest, and in the event of something extreme like a coma/braindeath etc. just let the body go naturally, and peacefully. Don't try to keep it alive by way of technology. Once the brain is dead, what's left of them? Cold flesh? It sounds harsh, but believe me, when a "body" is ready to "give up the ghost," it will. It needs no help or assistance. Just make me comfortable, and keep me company until I go....Just my 2 cents.