A Brief History of the Western

My wife's father has a seen a few westerns and finds them fascinating. So we're watching some westerns together. The question is, which westerns would you show to someone who hasn't seen many of them and wants to learn about the genre?

Here is what we have on the list so far:

• My Darling Clementine (1946) - One of John Ford's best efforts, Henry Fonda is Wyatt Earp. Victor Mature as Doc Holliday, does Hamlet. Cinematography to die for.
  
• Red River (1948) - Howard Hawks directed this early John Wayne vehicle.
  
• The Searchers (1956) - John Ford directed one of John Wayne's greatest efforts. Wayne is not just playing John Wayne here, he's angry, unbalanced, dangerous, animal-like - not the protector of order he later became.
  
• The Man Who Shot Liberty Valance (1962) - A lawyer at my old office said this was his favorite film. Jimmy Stewart and John Wayne do politics, gunfire. Ebert has not formally revied the film that I can find, but has an interesting take.
  
• Once Upon a Time in the West (1969) - Incredible to me that this was made in 1969, while Gunsmoke was still on TV and John Wayne was still in full voice. Ebert, in a rare miscalculation, does not regard the move as among the best, and blasphemes by criticizing Claudia Cardinale's performance. I've seen all but one of these films, and for me this is the one that most rewards re-watching, and has the most to say.
• And I know we have to finish up with Unforgiven (1992) - I've never seen it! Everyone says it's great, as does the Swami.

Which leaves a couple of questions - what were the greatest westerns of the 70's and 80's? And should we include some pre-war films as well? And are we going too heavy here? Maybe we should dig up some Roy Rogers or Lone Ranger TV shows? And what about Shane (Ebert: "he has...issues")?