Howard Hawks made so many fantastic films it's hard to choose a favorite, but I think Rio Bravo comes close--this is on my top five westerns list. This is a perfect western, and I think one of John Wayne's best performances. I agree with the comment that though the Duke and John Ford had the more celebrated partnership, Howard Hawks got the best performances out of him. Anyway, I LOVE this movie.
It's long but you hardly notice the length because the action is so continuous; the storyline is great and no more predictable than any other western (ie, you can assume the bad guy gets his in the end); the cast is awesome include Duke, Dean Martin as a drunken deputy struggling with his demons, Ricky Nelson as the cool Colorado, the beautiful Angie Dickenson as the unnamed "Feathers" and John Wayne's love interest, and the ever-memorable and ever-reliable Walter Brennan as the jail-keeper. I believe this one was also written by the talented Leigh Brackett.
Not sure why the team chose to rehash this beautiful film in "El Dorado". . . .also enjoyable but made less so by th fact that I can't help but compare it to Rio Bravo.