Cary Grant made four films- Suspicion, Notorious, To Catch a Thief and North by Northwest- with my favorite director, Alfred Hitchcock. Grant also referred to Hitch as his favorite director, and Hitch called Grant "the only actor I ever loved in my whole life". I've seen all four of their films together, and enjoy them all, so I decided to say a bit about each of them.
I would say Suspicion is probably the weakest of the four Grant/Hitch collaborations. Not that it's a bad film- it isn't- but I find the other three films they made together to be much better, one reason being because of the changes made to Grant's character in the film versus the original novel Before the Fact written by Anthony Berkeley. **SPOILER ALERT**. In the book, Grant's character kills Fontaine. However, the studios objected to this as Grant was one of the biggest stars in Hollywood at the time and they feared playing a murderer would ruin his image. Thus, the ending was altered, much to Hitch's objection. I would have liked to see the ending as it was in the novel, since Grant rarely played the villain in any of his films.
Notorious is one of Hitchcock's most acclaimed films, as it contains two of the most remembered scenes in film history. The first begins at the top of a staircase as Hitch slowly zooms in on Bergman showing a key hidden in her hand. The second is a two-and-a-half minute on-again/off-again kiss between Grant and Bergman that went against the Production Code, which stated that a kiss could be no longer than three seconds.
This is my favorite Hitchcock film for many reasons, one being the wonderful chemistry that the two stars had together.
Each of the four Grant/Hitchcock films features a car chase scene, the one in To Catch a Thief taking place in Monaco- reportedly on the same road where Kelly's fatal car accident occurred on September 14, 1982, after she supposedly had a stroke while driving.
North by Northwest is most remembered for the iconic crop-dusting sequence. While Grant waits at an isolated bus stop, a biplane is, in another character's words, "dusting crops where there ain't no crops". The plane flies toward Grant, barely missing him. You can watch the scene here if you're interested.
To sum it up, the four films Cary Grant made with Alfred Hitchcock are all worth watching. I'd recommend them to any classic film fan.