The Dark Knight was just as spectacular as everyone thought, breaking records at every turn and becoming the most groundbreaking superhero film ever.
Now what?
Am I the only one who isn't really looking forward to a sequel to the biggest blockbuster of the decade? Sure, I was hyped as hell for The Dark Knight immediately after seeing Batman Begins in the theater. The ending to Batman Begins was incredibly intriguing, mostly due to Joker being introduced.
The Dark Knight obviously blew Batman Begins away, but at the end the story felt... complete. We got the perfect Joker, Dent's arc was incredible and everything else was absolutely groundbreaking.
I'm not saying we shouldn't get a sequel, it will happen no matter what, but why all the speculation so soon and why is everyone buying into it? I guess it's true that us Americans have incredibly short attention spans and cannot appreciate a film for what it is after it's released rather we want to see if and how they will top it (which it isn't even certain that Nolan(s) will return.)
Another reason I don't see why everyone is so excited is because if these reports are true then producers are obviously pushing for the sequel far too soon. "Sources" say that producers are screaming "PENGUIN, RIDDLER, CATWOMAN - HOFFMAN, DEPP, JOLIE!" although Nolan has stated publicly that he has no interest in Penguin and Goyer has denied Catwoman, but teases at Riddler. If this is true it's terrible news because this will just keep Nolan from returning rather than encourage him. One of the reasons The Dark Knight was so hyped (atleast for myself) was the "unique" casting of Ledger, never before have we seen him play a role like this. The new casting rumors are just boring.
Now, here is my opinion on what a sequel should or most likely consist of.

The most obvious and likely choice for a villain for the next film will be Riddler. When a lot of people think of Riddler they think of Frank Gorshin or Jim Carrey and people would mistake Riddler for being too much like Joker. The truth is Riddler isn't really anything like Joker. Joker is obviously sociopathic but Riddler is just damaged. Also, Nolan bases his Batman characters from the works of Joseph Loeb and Loeb is known to portray Riddler as a small, intelligent yet cowardly crook (Batman: Hush is the only exception.) I would suspect Riddler being a Zodiac-type serial killer on the loose in Gotham, but there has been other ideas floating around as an investigator who is hired to capture Batman since he is on the run as a fugitive at the end of The Dark Knight. Both of very worthy ideas.
My personal pick to play Riddler is...

Jeremy Davies!
Jeremy Davies is an incredibly talented yet under-rated actor. He was recently seen in Rescue Dawn (which starred Christian Bale.) I also like Nolan's taste in actors and feel that Davies would fit very well into the Nolan world of Batman. Davies just seems like the best choice.

My personal secondary villian would be Black Mask. He is much like Bruce Wayne... only if Wayne would a messed up evil gangster. He was supposedly in the first draft of The Dark Knight so I would bet that he will make an appearance in the next film.
My personal pick for Black Mask would be...

Guy Pearce!
I like this pick most because Pearce isn't in nearly enough films (one of his latest, The Proposition is phenomenal,) he's worked with Nolan in the past (Memento,) and he's a great actor to take on Bale. It may be a long shot but it's just a dream pick. And he's got a skull-like face to fit into that Black Mask...

What about those Penguin rumors... pretty ridiculous in my opinion. Hoffman as the Penguin is a bit dumb as Nolan has stated he'd be more excited having Hoffman in the film rather than having Penguin as a character. But I'll give my opinion who should play one of the most uninteresting Batman villains...
Toby Jones!
I think this is the most interesting take on a boring character. I could see him being a character much like Bruce Wayne only very jealous of him because of his deformity. I don't see this happening... not as long as Nolan is writing and directing.
Catwoman would be a very difficult character to portray on screen. She's a woman in a cat costume that steals stuff. Since she and Black Mask have had a past in the comic books I could see it maybe happening, but not likely. Angelina Jolie is probably the lamest most boring pick. I don't get Jolie in action films because her arms are as thin as some of those Ethiopian kids.
My picks for Catwoman are...

Rhona Mitra!
Best known for her roles in Nip/Tuck and Doomsday I feel she is a great choice as the woman in the leather outfit. Not only does she look extremely physiqually fit (not anorexic) and she has an incredible amount of sex appeal. So far she is my favorite choice, but plenty of women could fit the role such as my other favorite picks...

Emily Blunt!
and...

There are also other villains such as Mr. Freeze, Clayface and Poison Ivy that won't see the light-of-day in Nolan's Batman films, but I won't waste my time with anymore of my comic book/movie geekery. Again, just my opinion for some perfect casting choices in the upcoming films even though The Dark Knight will keep me satisfied for however long the sequel takes.