Nolan's capable hands are exactly why a story like The Long Halloween could be incredible on screen. But, I would really doubt that WB is willing to put the Falcones so squarely in the limelight. Not to mention the fact that, y'know, Falcone is dead at this point. Which makes it that much stronger an argument to have Penguin rise to infamy in the next film, so I like your suggestion - and while I agree he shouldn't be the freakshow that Burton portrayed him as, I do think they would need to highlight the sort of "vengeful mongrel" aesthetic, lest he be seen as just another mobster aristocrat.
I have to say, Ghul's daughter would make one hell of a tie-in with the first film, but I'm not sure they want to touch on that aspect of the Bats saga again. Most casual Batman fans have no idea who Ra's Al Ghul is in the first place.
Still, I have to stand my my original assertion that Catwoman would work really, really well in this version of the Bats universe. Bruce needs a new love interest at this point, and Selena's shenanigans could make for one hell of a sordid love story and showcase Bats' detective work. Nolan's Gotham is the ideal setting to really dig into the complexity of Catwoman/Selena Kyle's character and the interplay between she and Batman/Bruce Wayne. Add the classic backdrop of a lunatic terrorizing Gotham (minor, please, I never liked Bane, but he deserves more than just peripheral villain status, IMO), and you have a good Batman movie.
Solomon Grundy,
Born on a Monday,
Christened on Tuesday,
Married on Wednesday,
Took ill on Thursday,
Grew worse on Friday,
Died on Saturday,
Buried on Sunday.
This is the end
Of Solomon Grundy.
Zombies sell tickets, gang. Fact.