Hey Timbuk,
Be sure to check out the “Required Viewings” thread for a quasi-complete list of shows, movies, literature and music referenced on the show.
As for my personal “required sci-fi” movies I would recommend the following:
SCI-FI
Back to the Future Trilogy
Truly a classic. In fact I kind of assume you have probably already seen it. Required viewing. Let’s move on.
The Fly
Seriously brilliant, seriously disturbing movie. Must see once, don’t recommend twice. So much in modern culture references this you will probably spend half the movie saying, “Oh, this is where that comes from”
Highlander
This is a fundamental. Perhaps more fantasy than Sci-fi, still required viewing. Do not watch the sequels, just this one.
Independence Day
Lower your suspension of disbelief on this one and cook up some popcorn. Wil Smith in Sci-Fi? Awesomefrakingtastic. His lines alone make the movie worthwhile (and now you will understand every other quote on GWC)
Matrix Trilogy
'Nuff said.
Men in Black
Wil Smith does Sci-Fi again. This is lighthearted and fun fare.
Real Genius
Another classic. Get past the coldwar and this is a seriously funny movie. Here are two of my favorite snippets (although, in all honesty I can quote from this all day long):
Chris Knight: Kent puts his name on his license plate.
Mitch: My mom does the same thing to my underwear.
Chris Knight: Your mom puts license plates in your underwear? How do you sit?
and
Chris Knight: This? This is ice. This is what happens to water when it gets too cold. This? This is Kent. This is what happens to people when they get too sexually frustrated.
Serenity
I know you said you had seen it, but…sorry, I can’t possible make a list of required Sci-Fi without including this. (You HAVE seen Firefly, yes?)
Tron
Dated and awesome. Concept alone should bring you back again and again.
Horror
[SIZE=2]I will be the first person to state I am not a big horror buff. I want to be clear here, when I think horror I am not refering to the modern sadistic gore porn that is out there (I am looking at you Saw and Hostel). There are a few movies that I have seen that I would recommend that scare you more by what you don’t see than what you do. Or are just fraking scary.[/SIZE]
Halloween
There can be only one. The original is the perfect horror movie. Slowly build up the fear and loathing than spin the audience around. Awesome.
The Hitcher (the original 1986, not the remake)
Because, honestly, anything with Rutger Hauer has to be good. Seriously tho, this is a classic edge of your seat horror movie. This will frak with your head.
Jaws
Again, classic. This is horror through narrative and brief glimpses of the shark. Just see it.
That is it off the top of my head. Would love to hear what other people think.