Re: How to avoid rehashing elements from the Nolan Trilogy
Visually: Gotham, Batcave, Suit/Color, Batmobile.
Other: More in depth with detective skills, same with fighting, Grayson's POV, different villains as much as they can, never thinking of leaving the life/always obsessed with being Batman forever. Quieter when inside the suit.
Arkham Asylum as a story is even appealing when you look at how you can make a different film. Only show him as Bruce Wayne in Wayne Manor/Batcave/Public in the beginning and end of the movie. In between he's locked inside Arkham Asylum. There's a point towards the end where he could leave no problem but he has to stay longer to end something important inside.