Has anyone mentioned "The Shootist" yet? That was one of the best I have ever seen. Lauren Bacall gave an excellent perfornmance and both John Wayne and James Stewart were in cracking form. It had the theme of a gunfighter, who had outlived his time and had to face death with dignity. It may have been John Wayne's best ever film.
Someone mentioned "Destry Rides Again" earlier, which is another of my favourites. Marlene Dietrich's punch up as "Frenchie" at the end is one of my favourite western scenes.
Two oddball westerns of the early seventies, both of which I enjoyed, were "Hannie Caulder" starring Raquel Welsh as a raped widow turned gunfighter seeking revenge and the comedy "The Legend of Frenchie King", with the unlikely leading roles for Brigitte Bardot and Claudia Cardinale. The latter, by the way, was in "The Professionals", which was another half decent film with an all star cast including Burt Lancaster.