I dont really care who they cast for JLA, except i do care about Tom Welling being superman. I think he will be the 2nd greatest superman of all time behind Chris Reeve. It would be a huge mistake for welling or the WB not to make this happen. Everyone talks about smallville baggage. so what if you are thinking about clark kent from smallville when your watching welling as superman. SUPERMAN is clark kent, clark kent was from smallville and so what if the character in this movie has adventures when he was a teenager when your watching him as a man in JLA. would it really ruin the movie for you. For the heck of it i'll give my cast for the rest of the JLA.
Tom Welling/ Superman
Ryan Reynolds/ FLASH
Jennifer Connelly/ Wonderwoman. I also think Megan Fox would be a good Wonderwoman, but she might be a little young.
Jake Gyllenhaal/ Green Lantern
Paul Walker/ Aqua-Man
I Know this would never happen, and it doesnt even fit into the theme of younger actors i have chosen. But i can only invision Batman as Hugh Jackman, So i dont really know who i would cast as Batman.