Things such as Forrest Gump, or The Lion King, for example. Movies that everyone should see at least once in their life. The sort of movies that live up to their legendary legacy after release. Add any movies you consider heavily underrated, also.
The big lebowski Pulp fiction Batman (with Michael Keaton) Batman returns Ghostbusters 1 and 2 Wayne's world 1 and 2 Bill and Ted's bogus journey Bill and Ted's excellent adventure Weekend at Bernie's Weekend at Bernie's 2 Donnie Brasco Scarface The Godfather 1,2 and 3 Rambo first blood Rambo 2 and 3 Rambo 2008? The shining A Nightmare on Elm street Canadian Bacon Cool Runnigs Naked Gun Naked gun 2 and a half Naked gun 33 1/3 Hot Shots Spy Hard The Burbs Event Horizon Escape from Alcatraz The Shawshank Redemption Hot Fuzz Walk Hard Papillon The Edge The Beach The cable guy The good, the bad and the ugly Two hands Edward scissor hands Con Air The running man Alien Aliens Lawrence of Arabia White noise Fargo CB4 How High Half Baked Senseless Hollow man Castaway Analyze this Analyze that Stripes Best of the best The informant
I'm not sure if these count as older or if you want to go all the way to B&W, but some 80s films:
Robocop Excalibur Karate Kid Neverending Story Amadeus Alien Willow Bloodsport Dragonslayer Robot Jox Tron (1982) Frankenhooker Re-Animator Total Recall (1990) The Running Man Kindergarten Cop What About Bob? Full Eclipse (1993) Road House Flashdance
These are a few. One that I consider really overlooked that's newer is Gattaca (1997) as kind of a poetic sci-fi.