Ok so maybe it won't be as easy for some of you, but partially to simplify my recommendations of classic Hollywood film, I felt like weighing in on another decade. If you haven't seen many films from the 1940's shame on you, get to a video store. Due to lack of foreign films made during WWII, this list will seem even more prejudiced towards American films than usual, but it was the golden age. 

1940 
The Philadelphia Story (US - George Cukor) 
The Great Dictator (US - Charles Chaplin) 
Fantasia (US - James Algar, Samuel Armstrong, Ford I. Beebe, Walt Disney, Graham Heid, Wilfred Jackson, Hamilton Luske, Bill Roberts, Paul Satterfield, Ben Sharpsteen, Norman Wright, Sylvia Moberly-Holland, Albert Heath, Bianca Majolie, Jim Handley, T. Hee) 
The Grapes of Wrath (US - John Ford) 
Rebecca (US - Alfred Hitchcock) 

1941 
Citizen Kane (US - Orson Welles) 
Dumbo (US - Samuel Armstrong, Norman Ferguson, Wilfred Jackson, Jack Kinney, Bill Roberts, Ben Sharpsteen) 
The Maltese Falcon (US - John Huston) 
Meet John Doe (US - Frank Capra) 
The Lady Eve (US - Preston Sturges) 
The Little Foxes (US - William Wyler) 
Hold Back the Dawn (US - Mitchell Liesen) 
Hellzapoppin (US - H. C. Potter) 

1942 
Sullivans Travels (US - Preston Sturges) 
The Palm Beach Story (US - Preston Sturges) 
The Magnificent Ambersons (US - Orson Welles) 
Yankee Doodle Dandy (US - Michael Curtiz) 

1943 
Meshes in the Afternoon (US - Maya Daren) 
Heaven Can Wait (US - Ernst Lubitsch) 
Casablanca (US - Michael Curtiz) 

1944 
Meet Me In St. Louis (US - Vincente Minnelli) 
Laura (US - Otto Preminger) 
Lifeboat (US - Alfred Hitchcock) 

1945 
To Have and Have Not (US - Howard Hawks) 
Children of Paradise (France - Marcel Carne) 
Mildred Pierce (US - Michael Curtiz) 
Open City (Italy - Roberto Rossellini) 
Fallen Angel (US - Otto Preminger) 
Scarlet Street (US - Fritz Lang) 
Way to the Stars (UK - Anthony Asquith) 

1946 
Somewhere in the Night (US - Joseph Mankiewicz) 
Brief Encounter (UK - David Lean) 
Great Expectations (UK - David Lean) 
A Matter of Life and Death/Stairway to Heaven (UK - Michael Powell and Emeric Pressburger) 
Beauty and the Beast (France - Jean Cocteau) 
The Best Years of Our Lives (US - William Wyler) 

1947 
A Gentlemans Agreement (US - Elia Kazan) 
Miracle on 34th Street (US - George Seaton) 
Out of the Past (US - Jacques Tourneur) 

1948 
Treasure of the Sierra Madre (US - John Huston) 
The Three Godfathers (US - John Ford) 
Force of Evil (US - Abraham Polansky) 
Oliver Twist (UK - David Lean) 
Unfaithfully Yours (US - Preston Sturges) 
Hamlet (UK - Laurence Olivier) 

1949 
White Heat (US - Raoul Walsh) 
The Bicycle Thief (Italy - Vittorio De Seca) 
On the Town (US - Gene Kelly and Stanley Donen) 
The Third Man (UK - Carol Reed) 
They Live By Night (US - Nicholas Ray) 
Twelve OClock High (US - Henry King) 
The Devils Wanton (Sweden - Ingmar Bergman) 

A few years may seem skewed to you, but I listed them based upon when they were shown theatrically (Oscar contention). I elected not to include short cartoons as my list would quickly turn into the Tex Avery show. Lots of "bubbling under" contenders which may or may not be added. I just hope I can throw a few more foreign films on that bunch.