Well, along with what others said, especially T2, BttF series, a few older Disney flicks(timeless), Apocalypse Now, Jurassic Park and Ferris Bueller's Day Off.. I'd add:
- Almost any other Disney flick. For example, 101 Dalmations. The style in that movies animation is simply beautiful. That will look fantastic in any generation. Also, Snow White may be the most watchable movie ever for being that old.
- Who Framed Roger Rabbit! This flick still nails everything it set out too. The 1940/50 undercover crime atmosphere, combining toons and people seamlessly, creating utter fear out of a villain killing a toon. This thing hasn't aged a minute and is still one of the most beautiful movies you can watch. For 1988 this is an insane achievment.