I think DC should do a Wonder Woman movie, its about time. DC has a strong female character equal to Batman and Superman in fame, but they just don't use her. She should have her own movie, that would bring in more of the female viewers too. Her story is sort of hard to tell, but once you get it out there it would be easy. Think how the 1st Superman film told his origin.
Then I would also like to see a Flash movie, its easy enough. A CSI guy gets struck by lightning and chemicals and can run super fast. Its not too convoluted or anything.
Not as much to tell as the GL movie, or even the Superman movie.
I'd also love to see a SHAZAM movie. a young boy becomes a Superman type. That would be awesome. little kids would LOVE it, and it would be a large epic wonderful wholesome movie.
I'd also like to see an Aquaman movie, he is a King of Atlantis who also protects the surface people. It would be cool.
Ooooh! AND, and, a CGI (possibly motion capture) JLA movie with a large awesome cast. You could get big starts with great voices who may not even look like the characters or are "too old" to play the part. Jolie or Bellucci as Wonder Woman, Bale could play Batman (or someone else), or you could go the Pixar rout and cast voice actors instead. The characters for CG film could be as stylized or realistic as they want. Look to Tin Tin, Incredibles, and Final Fantasy for that.