In no particular order. Writings to follow..........
The original series spawned 6 movies (1 to 6 imaginatively), then ST: Generations to link to the new series. The latter is not one of the better Trek story lines, but pays homage to the history of the franchise. Star Trek 1 is basically a stretched out TV show, fairly slow moving but beautiful. ST2-4 are good quality SF, 4 is light hearted and quite amusing in places. STV is a "heavy" SF film, not just because it follows the "popcorn" of IV and 6, to my mind, is the best of the series.
With Generations officially handing the flag to the crew of the Enterprise D, First Contact is an excellent yarn and gives us more "back story" on the trek galaxy. ST Insurrection is essentially a TV show and slow moving, even boring in places, bit too sentimental. The writers, producers etc, obviously took this to heart for the series finale (currently, 1 can hope!), ST Nemesis is an action packed romp with a bit of heart (and sadness), great end to the Franchise. (I'm ignoring ST: Enterprise TV series as they really dropped the ball badly with that one).
Wall-E
Another Pixar Classic, simpler story than some of the other films but very well imagined and, as you would expect from Pixar, superbly executed.
Predator 1 & 2, A V P, A V P Requiem.
Predator 1 is a very compentent action film, 2 just went for the gore angle. Alien V Predator has some brillant ideas that build on both character franchises but fails to deliver a great film, still enjoyable though; I feel unjustly under-rated. With Alien V Predator Requiem I think they couldn't decide what sort of film they wanted to make and ended up with a hodge podge, mediocre film; which is a real shame because there a lot of ideas from the first film it would of been good to explore (TV series?...) and the commerial failure of this film will prevent further productions I imagine. There were some good bits/ ideas in AVP Requiem but the production team didn't manage to make a coherent product, need lessons off Pixar!
Independence Day
You cannot beat this film for feel good, blockbuster entertainmnet, it almost created the Sci-Fi summer blockbuster market on its own; PLEASE watch on as big a screen as possible with the best sound quality you can and pretty loud (at least when the action is on!). If you don't like Will Smith being larger than life you probably won't like it and, yes there are some plot holes (though why so many people go on about Jeff Goldbloum being able to connect to the Alien computers I don't know, they were using our satellites!), but there's a lot for other film makers to learn from this movie re character development, sub plots, humour etc. One of my all time favourites.
Bladerunner
For imagery etc, just WOW! This film is probably a little slow moving for modern tastes (it is 30 now), but just outstanding in every way. Contrary to most Fans I actually like the version with the Harrison Ford voice over, though agree without is better. The latest DVD produced (The Final Cut) is the best to try if you've never seen it, (it has no voice over and the originally intended ending).
Star Wars
There's nothing I can say really; you could be into Science Fiction and spend your whole life just with Star Wars. Like most people I prefer the orignal trilogy to Episodes 1-3, I feel more attention was paid to pacing and characters. The volume of spin-offs is nothing but mind boggling; there are several hundred tie-in books alone, some authors do nothing but write Star Wars books and do quite nicely thank you! For more info just type Stars Wars in to a search engine and get buried.......Serenity. Film following the (criminal) demise of Firefly - see the SF TV page.
Joss Wheadon did a good job of trying to balance all the different needs of a feature film, whilst trying to keep the fans happy (they were the reason it got made.....) It lost a little of the intimacy of the TV show, (hardly surprising with the change of format) but did manage to tie off some bits left dangling from the series without making the movie slow moving or incomprehensible to anyone who hadn't seen Firefly; overall a great effort but not perfect, if the team get to make another hopefully they can make a immaculate film as they won't be trying to balance so many spinning plates - They set the standard with the TV shows!
Fifth Element
One of my all time favourites; best film for Mila Jovich, (very believable as an alien!), good film for Bruce Willis, humourous, good action, good plot; what more do you want?
12 Monkeys
Close Encounters
ET
Silent Running
2001, 2010
Day after Tomorrow
Alien, Aliens, Alien 3 & 4,