Batman: Matthew Fox or Gregory Peck (I'm reminded of Alex Ross's paintings of Bruce Wayne which are all based on Peck and Matthew Fox's Racer X expressions and body movements reminded me big time of Batman. In the box seat scenes near the end of Space Racer he also looked like he could pull off a very dashing Bruce Wayne. He's my choice if Bale chooses to leave the role for whatever reasons)
Robin: My Dick Grayson would be a twelve year old...faithful to the story but if I was forced to choose an older actor to try pulling an younger actor it would be Emile Hirsch from Into the Wild and Speed Racer. Hmmm pattern going on here.
Barbara Gordon/Batgirl: This one is a tough one since the era of Batman I'm going for Babs would be a young teenaged girl. Perhaps a young Alica Witt as Babs.
James Gordon: Gary Oldman is perfect as Jim Gordon. I love the voice actor who does his voice on BTAS but for a live action Batman, Oldman is my guy.
Alfred Pennyworth: This is a tough one since I like both Michael Gough and Michael Caine. Both bring their own take to the character. I'm going to have to go with a younger Gough though with a touch of Caine's humor.
Harvey Dent/Two-Face: A younger Mel Gibson. Every time I see The Man Without a Face I think he could have played a brilliant Two Face.
Joker: Mark Hamil
The Penguin: I like the suggestions of Philip Seymore Hoffman as Oswald Cobblepot.
Scarecrow: Christorpher Lee
Ra's Al Ghul: David Warner
Catwoman/Selina Kyle: Rachel Weisz
Mr. Freeze/Dr. Victor Fries: Patrick Stewart
The Riddler: Johnny Deep (sort of like this suggestion for some reason)
Taila al Ghul: Penelope Cruz
Poison Ivy: A Young Julianne Moore or Amy Adams current.
Lots more just can't think of them right now and we should do this for our dream superman cast.