As I've watched, I've followed along with the IMDB trivia pages for each episode, basically keeping a browser tab open for the last few months and advancing it from episode to episode as I went. I've looked up a few of the actors to see what they've done since, or to confirm, "Wait, was that...?"
Warning: There are spoilers below for "The West Wing."
One of the trivia tidbits that caught my attention was the pivot the writers and producers decided to take when John Spencer, who had played White House Chief of Staff Leo McGarry for the bulk of the series and ultimately jumped in as the vice presidential candidate alongside Matt Santos, suddenly died of a heart attack. Leo had been sidelined with a heart attack himself, and the parallel was tragic.
Originally, they'd apparently planned for Republican centrist Arnie Vinick, played by the amazing Alan Alda, to win the election as the series drew to a close. But, the producers decided after John Spencer died, and the viewers had to deal with that heartbreak, it was unfair to follow that with a loss for the Santos/McGarry ticket. Leo was off-camera for a couple of episodes after the scenes John Spencer had shot before his death were used up, and then the character was found in his hotel suite and rushed to the hospital -- without being seen on-screen, of course -- where he died, just hours before the polls closed on Election Night.
The seventh and final season of "The West Wing" opened with a flash-forward scene to the future, with several characters gathering for the opening of the Josiah Bartlet Presidential Library. It's almost a shame they didn't end the season by returning to that moment, but I do appreciate how the series ended, including a scene with the newly inaugurated president asking, "What's next?" as President Bartlet had in the very first episode.
On this pass through the series, I noticed that John Spencer wasn't in that scene at the Bartlet Library. He wasn't the only one, but in retrospect, it was a haunting choice.