I second The Song of Bernadette. Great movie. The last third of the movie, after Bernadette enters the convent, is very moving and a great example of her humility and redemptive suffering that we should all follow. Other than a somewhat silly platonic romance between Bernadette and a boy named Antoine, I felt it was a really good portrayal of the saint, and a movie that every Catholic should own.
Francis of Assisi is also a great movie, a reverent portrayal of the saint free from the hippie influences of several later films. Once again, a movie every Catholic should own.
I also agree with Thorn on Therese. It's not that there's anything necessarily wrong with the movie, but by no means does it do St. Therese justice. And I'm not really sure why she has a mustache after she becomes bedridden. That always disturbed me somehow.