A lot of very fine movies fall into the "1970s or older" category. Agree with praise for the "Topper" films.
Here are a few more "old" favorites, in no particular order:
Caesar and Cleopatra (Claude Rains, Vivian Leigh, 1945). Not as "big" a movie as the Liz Taylor/Richard Burton version, but better dialog, acting, and direction.
Zulu (Michael Caine, Stanley Baker, 1964) One of the finest war films made.
To Hell And Back (Audie Murphy as himself, 1955) The grenades actually smoked before exploding.
Sergeant York (Gary Cooper, 1941) A fine telling of Sgt. York's story.
Comrade X (Clark Gable, Hedy Lamarr, 1940) A comedy about the Bolsheviks.
Spartacus (Kirk Douglas, 1960) Superior to any of the recent remakes
Ben-Hur (Charleton Heston, 1959) FAR superior to the recent remake
The Ten Commandments (Charleton Heston, 1956) FAR superior to the recent remake
Forbidden Planet (Earl Holliman, Leslie Nielson, Walter Pidgeon, Anne Francis, 1956) Inspired by Shakespeare's The Tempest, a solid contender for best sci-fi film ever made.
The Adventures of Robin Hood (Errol Flynn, 1938) A more "fun" movie than any of the remakes.
Horatio Hornblower (Gregory Peck, Virgina Mayo, 1951) One of the best of the "wooden ships and iron men" movies that were popular for a while
The Day The Earth Stood Still (Michael Rennie, 1951) Not to be confused with that abominable 2008 remake with Keanu Reeves.
The Three Musketeers (Gene Kelly, 1948) This film - particularly the 1st half - is better than any of the later remakes.
Call Me Bwana (Bob Hope, 1963) Funniest scene: Cannibal child comes up and pokes Bob Hope. Cannibal child's mom pulls him away, tells him "Don't play with your food."
The Sherlock Holmes films with Basil Rathbone were pretty decent.