Some of my favorites, besides what you have mentioned above.....
The Westerner (Gary Cooper and Walter Brennan)
My Darling Clementine (Henry Fonda)
High Noon (simply a classic)
Santa Fe Trail (Errol Flynn)
Gun Fight At OK Corral
Butch Cassidy and the Sundance Kid
The Man Who Shot Liberty Valance
When it comes to John Wayne and Clint Eastwood westerns - I love them all. I've come close to having them all in my collection; but if they're on TV I'll still watch them. But IMO, you can't beat a John Ford or Howard Hawk western.
Some of my favorites though....
The Searchers (just bought it in Hi-Def)
Chisum (classic Wayne)
While I liked True Grit, I really enjoyed the sequel Rooster Cogburn with Hepburn. What a duo.
The Sergio Leone trilogy was excellent. But one of my favorite of Eastwood's is The Outlaw Josie Wales.
Sam Peckinpah's Pat Garrett and Billy the Kid is also good. I didn't really care much for The Wild Bunch w/ William Holden.
Over this past year I've been making the effort to try and find/collect the old 50's/60's TV western series I grew up enjoying. Shows like Cheyenne, Sugar Foot, Bronco, Have Gun Will Travel, and others.
Thank God for the Encore Western channel. I watch it religiously.