Assuming that's true I think drifting to sleep underneath the Earth in the same way people on earth drift to sleep underneath the moon would be pretty darn awesome.
I have no idea if that sort of thing was available on the moon missions, but it would probably the most convenient option if you've got nitrogen available.
http://video.google.com/videoplay?docid=-8068091823725414405...
He comes to the conclusion nitrogen would be the most humane (euphoria, then painless death). Apparantly it won't get used because those states that still use the death penalty find this way of leaving the temporary for the infinite a bit too easy on the convicted... (forward to 45:30 in the video).
I remember an interview with Aldrin where he was asked how he would have spent his last moments in case he got stranded on the moon, and he answered he'd be trying to get the engine working :)
These men would have had very little to no hope of a rescue, but they would have had plenty of air left to choose when they wanted to die. I can think of no more beautiful sight at death than your entire world and species.
“It was said that when they were in use, astronaut candidates would be asked to get in one. After fifteen minutes or so, the candidate was asked how long they thought they had been in. If the candidate was not hysterical and guessed anything under an hour, they passed!”