With the casting of Wonder Woman, which I'm ambivalent about, you might as well make it about DC's big three. Do a short origin clip for Wonder Woman make her a goddess like Thor, hell have Steve Trevor explain on a off cuff remark. Leave Batman's origin more or less the same since we have seen about 100 times now, and boom you got a great setup for JLA. But if the rumors that there are going to be more Justice League cameos, just fucking call it the Justice League, and be done with it. Reverse Marvel it and do the big team up first then spin each character off onto their own movies.
(pic from Ryan Sook)