Lots of good ones. I'll throw in Memphis Belle (1990). After safely landing, the always-serious captain (Matthew Modine) asks his crew about the stowed away bottle of champagne and tricks them by spraying them in celebration. A terribly cliched movie though.
How could I forget? Blade Runner. (The Director's Cut, of course.) "It's too bad she won't live. But then again, who does?" Deckard nods quietly in understanding, steps into the elevator, doors shut--BAM! Cut to black, credits roll, Vangelis music kicks in. Great ending.
Captain America is another one with an ending I love. It's sad but works so well because the great script actually gets us emotionally invested in Steve and Peggy. (Far more than the Iron Man movies ever do with Tony and Pepper, or Thor did with Thor and what's-her-name.) For a big budget summer action flick, it just about brought me to tears at the end and really worked on an emotional level.