That's a pretty good list. I have a few differences in how I look at lists like this, though.

I generally lump major series together, unless there's a real standout entry or a long series. So I agree with having just Star Trek 2 in it, but think Star Wars 4 and 5 should occupy 1 spot and include ROTJ. For cases like Terminator, where there are a ton of crap movies, I'd put the original and 2 in a single slot.

There are a bunch of classic movies missing, too. Soylent Green, Invasion of the Body Snatchers, Forbidden Planet, Metropolis, etc. Personally, I'd have Dark City, The Last Starfighter, Short Circuit, maybe Iron Man, Black Panther, or Age of Ultron (some Marvel entry). A nod to anime should also be in there, even if it's just Akira. Others I'd might have in there if I ever sat down to rank these things in order: Total Recall, The Running Man, The Lawnmower Man, Cube, THX 1138, The Fly, MiB, Mad Max, The Thing, Close Encounters

Probably not making the list, but noteworthy conceptually: Minority Report, Johnny Mnemonic, Contact, Children of Men, Contact, Donnie Darko, Looper,

If they want to include movies that were great within their times or some specific context, the original animated Transformers was a crazy, but noteworthy departure from the franchise's previous media. Galaxy Quest and Space Balls aren't philosophical masterpieces, but definitely high on my list.

For kid friendly stuff, Batteries Not Included, Space Camp, Flight of the Navigator, and E.T.