I think most people have experienced a 'best last day' with someone. I've written about them before so I won't go into detail, but with my wife, it was a New Year's Eve about a month before she was gone, when we drank fake champagne together and played Parcheesi. For a small window of time she felt pretty good but was tired so I put her to bed at 10:30 and simply smiled and cried until midnight. With my dad, it was when I accidentally tipped his wheelchair in the soggy grass and fell over him as it rained and we laughed and laughed.
Of course, I didn't realize what sort of fortunate days they were until later.
I'd like to think that everyone has the opportunity for such a moment and it makes me curious about the experiences of others.