I agree with those saying "Like Dick Grayson, not sure about Robin in a movie." Maybe just skip to Nightwing with, yes, more of a partner approach? Especially if DC does a "multiple superhero" thing like Marvel's doing.
^That's been my thought in this regard too. If they want to keep to a more realistic approach just jump right to one of the post-Robin identies, Red Robin, Nightwing, or Red Hood.
Personally, I would love to see them do a movie with the Stephanie Brown. I don't know the character myself, but I think it would be interesting to see the mass public's reaction to a girl Robin.
Does the general public know about the identities other than Robin?
These movies, while sticking pretty well to the source material, are seemingly geared towards a non-comic-reading audience.