It is a waste of a good Batman, both in casting and plot arc, to send the dude to New Orleans to fight a giant crocodile. I've said this before and I'll say it again. The only place it makes sense for this iteration of Bruce Wayne to go is Catwoman.
We've had the rise to responsibility. We've had the abuse of power (which I think worked because it was broadly topical, and an example of an abuse of power that the no presidential administration had tried). We need to return to Wayne's interior self. And frankly, given Rachel's death, and the messy transition of the recast from Katie Holmes to the superior Maggie Gyllenhaal, it makes sense to deal with both interpersonal relationships and gender. We haven't had a contemporary superhero who deals with real sexual darkness (the metaphorical abortion in X-Men doesn't count), much less a superheroine, and it's about time for both. There's an element of sadism and masochism in the kind of superheroics Batman represents. He beats people with his fists, he exposes himself to extreme danger without healing powers. And his character's just been stripped of both his chance for happiness and his illusions. Send the guy on a date where he's out of control and maybe in some danger himself. Show that the abuse isn't just potentially about the gadgets. Give us a woman who inflicts real damage when she scratches.
And most of all, don't waste the end of a sophisticated trilogy on a too-time sensitive New Orleans story. Nolan should keep making movies about the essential nature of Gotham. And the darkness in humanity, rather than in beasts.