I have a few ideas for trailers floating around in the brain...
A Lex/Batman one:
It starts with a shot of the inside of a massive office. You can see lights of a city outside massive windows, but nothing more. The camera pans to one side of the room and there's a figure at a huge desk. The figure can only be seen in shadow at first, but the camera moves in closer and the dim lights outside illuminate the figure of a man, just a bit. He's wearing a business suit and has a bald head (I wonder who? lol). He's looking down at something hidden behind the desk in his hands. As he does this, he speaks:
"Do you remember...what is was like...before he arrived..."
The bald man looks over towards the other side of the room as he says this and then back down at whatever is in his hands. Another voice, a deeper voice from somewhere in the room replies to the bald man:
"He's been here for a while." It's a matter-of-fact, unamused tone.
"Yes, certainly," the bald man replies with a bit of a chuckle, "he was here...hiding from us...Letting us enjoy our free will for a few years more..."
There's a brief silence and the bald man speaks again:
"Isn't that ironic? A creature like that hiding from us. Weaklings that we are..." He chuckles again...bitterly. "I have never felt weak before. Not until he came."
The deep voice replies: "You're afraid of him, aren't you?"
"Yes. Always."
The camera then shows us what the bald man is holding. It's the MOS S shield drawn in blood on a small plank of wood.
"They wrote it in their blood. So desperate for their calls for help to be answered and it was all they had...they drew his symbol in their blood so he would know which building they waited in...for him to find them and take them away from the ones responsible for that same blood. Can you imagine such a thing? Has anyone every done such a thing for you..."
"Maybe." Still unamused.
A small laugh. "Well, he doesn't even need their symbols, does he? He can find them easily. He can see everyone...like a God. And yet...they offer him the kind of love that's written in blood. Many years...I have tried to earn such a thing...and he has it in two short years..."
"I know. He told me the same story."
"It's unnatural, you know. Such devotion."
"I know."
"You're afraid of him too."
Silence follows. The bald man lays the plank of wood with the symbol on the desk and stares towards the other voice.
"You are. We all are. Secretly. Brave men...all afraid of the thing we cannot stop or become. We don't live anymore. We do what he says, Mr. Wayne. And nobody realizes this, but us. Look outside. Look on our very streets and tell me what you see."
"You know what I see."
"Yes! An alien symbol! Those people out there...those weak, ignorant people use an alien symbol in place of a human word..."hope." Why is that, Mr. Wayne? Why do they call out to him instead of their own kind? Instead of me? Instead of you?"
"You know why."
"Because no one can save them but him, isn't that it? Well...I remember the days when our kind pulled ourselves out the abyss and we didn't have to sacrifice half of my city to earn the privilege! Something happened, Mr. Wayne and it must be stopped..." He's interrupted by the other voice:
"I know what happened! You don't think I saw his triumphant introduction?! I saw it all..."
"You saw humanity lose its place as the dominant species on this planet that day, Mr. Wayne! That's what we all saw and no one knows it but us."
"And so we should stop it, shouldn't we?"
"You knew it that day and yet we've allowed it to go on far too long. They need you, Batman. They need us to be what we were before he came."
"I know they do." He sounds resigned and sorrowful.
"He trusts you?"
"Yes"
"Well then, Mr. Wayne. We have a common problem and an obvious solution, don't we? Is that not why you agreed to come here?"
"Of course."
"Then tell me," the bald man gets up from his seat as he says this and extends his hand to the other figure who is now in view and has the distinctive silhouette of bat ears and a long cape illuminated by the city lights, "has there ever been a time when men fought a God and won?"
The batman shakes hands with the bald man and says:
"There will be."
The final shot is the two of them staring off into the city's night skyline through the huge office window.
We never really see the context of this. Is Bruce really with Lex? And if he is, why? What is his relationship to Superman? Is one of them tricking the other? It raises more questions than answers and perhaps would work better for a teaser.
t:
symbols with shots of Metropolis and Gotham. 
