great thread, makes me think on many levels.
I didn't think SR was a bad movie, I quite liked it. Infact I really liked it (Hulk aswell). That being said, I can identify with those who wanted a more popcorn superman movie, because the film is lacking in action, and there is almost an hour long break in the middle of the movie with minimal action.
Now, we've all seen in the recent past, that pure action movies, with less story don't fare so well, especially the big ones (Matrix Reloaded comes to mind). Today's modern movie market requires a plot, and some emotion. It is due to a change in the market, with an increased female element that is being catered to (this is not a bash on ladies, it's the advancement of female integration which is unavoidable). And as a result, movies like commando are not big time winners like they once were. Applied to superman, there is a need for that emotional rollercoaster and interpersonal relationships. SR had this, and it was well done IMO (although outside of the standard superman narrative).
Now lately, even the the comics, Superman has often be portrayed as a lonely figure. Maybe even a brooding one at times. This all goes hand in hand with being the most powerful being on the planet. And I think Singer has shown that this can translate onto film well. Again, SR had oodles of this and it was good.
SR, had some major narrative implications though. Mainly surrounding the interpersonal relationships he had. Namely, Richard and Jason. They are not a bad thing, and worked well on screen. The only thing that really bothered me in the end, was that feeling that 'this is WB, and it could really be ruined in the end, if they go the wrong direction' (As WB is so well known for doing). That is my only real concern, because although this movie took a risk by introducing Jason, but it avoided all the difficult stuff by ending before it began (ie. interaction b/w supes and Jason, Richard and supes, and the rest of the family). It is at that point where things will get iffy (but that hasn't come yet). I think that most of the hesitancy about Jason is the fact that we fanboys are slightly nervous about what will happen with the character? It could be really cool, but it could also be horribly terrible.
So I think that SR has layed a great foundation for a franchise, even though it didn't smash the B/O (which is just a stupid move on WB's part (release date)). All the elements of Superman are there. Yes, Supes was a little depressing, which is so not superman, however, this was a depressing story. He was meant to be depressing. Will that continue for a sequel, I think not. He left on a search for his family, returning when his quest was fruitless, realizing finally that he really is the last of his kind. Only to return to earth, to discover that what he was looking for was right here.
SR ended, with Superman being where he should be. Everything (narratively speaking) is in the right place for a 'normal' superman movie, with lots of action and all the boyscout fun. The only twist is that Jason is still around, that's really the only carry over from SR (emotionally speaking). A sequel to SR will have an emotional base left over from SR, but will more than likely incorperate more action, and more 'supermaness' (as per the critique it is getting on this years release).
So stagnant, or move forward? Well, I was actually expecting this movie to be stagnant in the first place. A week in the life of Superman one could call it. But it turned out not to be. But how should the rest of the franchise go if it gets a chance? I'm a fan of how the original franchise grew. The opening 2 movies, being direct sequels of each other, then sequels beyond the 2 part opener would be stagnant as described above. That way the universe, and audience are schooled in the character, that sequels can just jump right into the action, w/o having to define the characters, and settings.
On the other hand, I'm also a fan of how Startrek organized their franchis. The opening movie is self contained, but then movies II, III, IV and V are all linked by one long story arc (yet each film is self contained). And then the rest of the movies were one hit wonders.
I say, first two movies be direct sequels, fleshing out the characters, creating a universe in which the characters operate, getting the setting right, and tying up loose ends (Jason and Richard). Let SRIII and the future continue on at a stagnated pace. Allow them to be self contained one hit wonders. Just remember, for me, that all hinges on SRII being a badass mofo movie.