I can't speak for the organizers (would I even know their language?), but I can give my perspective as a long-time marathon attendee.
I divide science-fiction cinema into three categories.
1. Classics, pre-1968.
Why 1968?
2001 a Space Odyssey. Now whatever your personal opinion about Kubrick's opus, if you listen to writers and directors who were pioneers of the next generation of modern sci-fi (Lucas, Scott, Spielberg, Carpenter, O'Bannon, Corman, etc.) - they almost universally cite this movie as a profound influence.
That's a pretty critical transition point. Coming at the height of the moon race, it was paired with a quantum leap in film effects technology which would be replicated and refined for decades.
So personally, everything immediately gets divided into "Pre-2001" and "Post-2001" in my book. Some of the greatest works in film science fiction come before this film, but the look and feel of films after just hold a totally different and unique tone.
2. The Renaissance Years (1968-1993).
Why 1993?
Jurassic Park (see below). Honestly, there's no CLEAR boundary here, as there are fuzzy examples of the transition throughout the 90's. But it's as good a place as any to try and define a cutoff.
Essentially, from the mid-90s on, three critical things (and one tangential) start to happen to Science Fiction.
First, Special Effects once again leap into a new era ... the era of digitally generated effects comes of age. Sure,
Tron and
The Last Starfighter paved the way, but it wasn't really until
Jurassic Park came along that Hollywood felt like it had been proven (fiscally) that digital effects technology could open new doors to the creative process.
Second, the big-screen was really no longer the king of the castle. VHS and home theater had largely begun to surpass theater profitability in the 80s, and by the 90s DVD had become the new standard in entertainment viewing. No, cinema was not dead, but distributors were now approaching films with a different viewpoint ... no longer did a film HAVE to make its money in domestic or international box-office gross. Now films could be green-lit expressly for the purpose of a release to video.
Third, the rise of the Internet changed the way that films could be marketed and the speed with which "word of mouth" could expand a film's popularity. Digital distribution was starting to become a possibility as early as 2000, and the rapidly growing Internet was an information explosion unparalleled in cinema (or human) history.
Finally, on a more local scale, this was the crowning era of our own fledgling marathons. They were proven and still strong (if beginning to stumble) and the concept of being able to see new films as a premiere was really rolling into play.
So anything from before this rough 1993 date, but after 1968 ... those are the films that came out during my childhood. Those are the films that I remember seeing on the big screen with an audience when I was young. They're easily as important to me as anything which came before.
And let's not forget that some of the landmark films of science-fiction came during this period ...
Star Wars,
Alien,
Blade Runner, etc.
3. The Digital Age (1993-Present)
The title says it all ... continual refinements in digital technology led to a whole new effects world. Films can now be made on people's desktops and distributed entirely through the Intertubes with nary a film distributor having any say in the matter. The process has changed irrevocably, for better and for worse.
This is definitely a different era than it once was. And obviously new premieres are going to fall into this category. I also consider this the category for "recent sleepers" that people might not have had a chance to see. Films like
Slither,
Moon, or
Sky Captain and the World of Tomorrow are well worth seeing in the theater, but due to limited distributions a lot of people completely missed them.
Something like
Iron Man? Well, I'm not in the camp that you "need to have a recent big-seller" to draw people in. But that and
Star Trek were films the audience enjoyed seeing, so maybe they keep people in their seats a bit longer.
Anyway, that's how I split things up. For my money, I like to see marathons generally divided between the three. Old-Classics, Near-Classics, and New-Classics. Start with 3 of each and then fill in the last few slots with whatever else is available, thematic, and takes your fancy.
Oh, and show
Zardoz. Always show
Zardoz.
