Doug R. mentioned 'Rio Bravo', one of my favorites with a nice musical interlude with Ricky Nelson and Dean Martin harmonizing on " My Rifle,Pony and Me",,then going into " Get Along Home Cindy Cindy" with Walter Brennan joining in on the chorus. Makes me smile every time I see it.
Also, not a straight cowboy picture, but 'Northwest Passage' with Spencer Tracy and Brennan, and Robert Young is very good.
Clifton