First of all, no A-list or B-list movie stars should be casted in the JL movie. A bad example of this is Superman Returns, which used Kevin Spacey, a well known actor, as Luthor while casting Routh as Superman, a unknown actor is totally off. It doesn't make any sense. If they're gonna cast unknown or relatively low profile actor, they should stick to it and not cast one A-list with unknown actors. Example of this is LOTRing.
SUPERMAN: Tom Welling and Brandon Routh should not be casted as the Superman in JLA. Brandon Routh need to be kept as the man that play Superman for all Superman movies. Tom Welling is not yet ready to be 'Superman'. He's best suited for miniseries.
The person that should play Superman in JL is ............(. I can't think of it right now.)................ I'll come back to it another time. I just wanted to write this.
BATMAN: Christian Bale and past batman actors should not repry their role as the Batman in JL.
The person that should play Batman is Antonio Sabasto Jr.
I remember reading something about him. He has a batman symbol tatooed on his arm. A Motorcycle that is batman inspired. He has the look and body to play Batman. He also know how to fight. He has done action movies in the past.
I'll come back to the rest of the other cast......................
If Miller doesn't cast Antonio Sabato Jr as Batman in JL, i'ma slap studio executive in the face with a piece of my opinions.