Haha. Alright, so if these are the beginning and end, what would you guys consider relevant material to the "middle", from Morrison or otherwise? I have a vague "Batman canon" in mind, but have never really formed much of one for Supes.
The continuity is slightly different between All-Star and Action, but generally I think they work well enough as book ends. Morrison has said in interviews he sees all of his work (or at least his Superman work) as holding to its own internal continuity, even when DC has said otherwise. For example, in Action, the Kents are both dead before Clark puts on the cape. In All-Star, Martha is still alive years into Clark's career. But Morrison continuity glosses over those details for a more broad stroke, spiritual view.
As for essential events "in between" I would say the Death of Superman tops the charts. It adds to the man's mythology and the quasi-religious aspects of what Superman represents to have him die and return.
I myself think that Clark's time with the Legion in the 31st century is also key to who he becomes; it brings with it a big picture mindset that is near-essential to how Superman operates. However, to balance it out, I also believe that later in life, Clark should return to the future, when the Legion is just forming (before they go back to the past to meet young Clark) and provide the inspiration for them to officially become the Legion. Clark inspires them, and they in turn inspire him. Time travel at its best.
The formation of the League. It illustrates the change over from outlaws each working in their own small corners of the world to a larger, more permanent effort to make the world as a whole a better place.
Marriage to Lois Lane. By the same token, her death (best in Kingdom Come, IMO) as well as learning whether or not they can have kids. For Clark, any aspect of a "normal" life he can actually have is sort of like a little miracle for him, and any time he learns that those things are impossible is just more reaffirmation of his role and burdens in life. So however that plays out, its a major event in his life.
The process of discovering his heritage of course, though that is more of a slow unveiling than a big event, in many cases. However, meeting Zod, discovering the Phantom Zone and/or Kandor.....any small piece of his homeworld would be a big moment in his life.
Oh, killing Zod and exiling himself to deep space. Thats a big moment in his life.
Kingdom Come. Clark realizes that he and his peers have become too heavy handed with the world, and they themselves have become part of the problem. I feel its part of learning where that perfect middle ground is, and KC pushes Clark to look at things he had ignored beforehand.
Just off the top of my head and in no particular order.
I completely and totally agree with the second point. I myself really enjoyed the aftermath of that though; seeing the world's reaction to his death, and the rise of the four Supermen. That was good. Of course, that was when I was first getting into DC so my memory may be biased. But regardless I thought we were talking about milestone moments in Superman's life, not quality stories. Superman fighting the Elite was a quality story, but boils down to being just a rough day at work.
Oh, Lex Luthor becomes President of the United States. That's a moment.
If you're (the OP) looking for pretty much anything major in the mythos, without much concern for whether it would properly fit in thematically or continuity-wise (which is what I have been assuming), then the second genocide of Krypton. The Son of Superman OGN explores a possible future just this side of dystopian as the child of Clark and Lois develops his powers and Superman returns to the world after being captured for years.
A robotic journey toward the American Dream: MADE in USA.
Also keep in mind that the landlady said that Vyn has manipulated Superman's history, pushing him down this New 52 historical path.
That means that he could have worked backwards from All-Star Superman, causing trouble along the way. Vyn most likely killed Clark's parents by cutting their brake line.
So this is the same Superman he always was, but an imp screwed with his timeline and really ruined it. Grant doesn't link it to Flashpoint and he probably wrote this premise before they rebooted. So this is one period of Superman's life as he makes his way forward, blurring canon and creating his mythology.
In fact I think I will go one step further.
This is the same Superman he has always been...Pre-Crisis, Post-Crisis, Post-Infinite Crisis etc. Vyn has been just messing with his timeline across all dimensions and realities, and this is just one of the many results in Vyn's efforts to break Superman.
Grant is basically suggesting that all the various incarnations of Superman in the past, present and any incarnation we get in the future and the variations in canon is due to Vyn, essentially making EVERY SINGLE Superman story in comics...and possibly all other media part of the official Canon. The Superman we are reading in the New 52 is the same Superman we read 20 years ago, the same Superman that fought gangsters in the 30's,and 40's had wacky adventures in the 50's and 60's, Worked for television as Clark Kent and gained a social consciousness as Superman in the 70's and 80's, Had his adoptive parents alive, Died and returned, married and then turned electric in the 90's and the Superman who found and lost his homeworld again in the 2000's. it's the same guy...It's ALWAYS been the same guy and Vyn has been tinkering with things.
So in other words with this story, Grant has done what he did with Batman, but in a much larger metatexual way. Everything is now canon because it all happened in some way.
I know DC will never officially state it to be the case, but yes, All of Grant's work on Superman can be concidered its own canon, and as a result, everything else over 75 years is now canon as well.