Comic Book Movies

I'm no comic book expert, but I enjoy many of the movies made from them. And, they are usually quite successful. But I'm curious, at what point do "they" stop making more sequals to a particular comic book movie? I realize the more sequals made, the higher the chance it will be a new director and/or difficulty of signing important cast members to return. And, the more movies, the less interest in the series usually.

I want to use the new Batman series as an example. I don't know a whole lot about Batman actually. But I know, like most comic books, Batman has lots of characters and villains. We know in "The Dark Knight" that the Joker will be in the movie. But there are so many characters and villains, how do you fit them all in the movies. If you don't make enough sequals, you won't get many of the characters in the series. Or, you run the risk of too many characters in one movie to fit them all in. But, if you make too many sequals, you run the risk of people losing interst in a 4th or 5th Batman movie (unless they were all like "Batman Begins").

There has been one Batman movie so far (under the new series). Can anyone tell me what most directors are thinking? You have this long list of characters (Catwoman, the Penguin, Two-Face, the Riddler, Robin, Mr. Freeze, etc, etc.) so who do they make sure gets in the sequals and who do they not mention? What order of characters gets introduced? Who are the "main" characters to be in all the movies? Is the "Batman" story every finished or any comic book story EVER completed? When does a series just finally end? Could "Spiderman" just go on and on and on? Adam referenced the villain "Venom" for the "Spiderman" series. Is there ever an end to all the villains in a story? Do they just keep coming up with new characters to keep fighting crime?

For those of you comic book guru's, what is your take?

Oh, and I read on espn.com today that Gary Sheffield is the nephew of former MLB pitcher/druggie Dwight Gooden. Does that strike anyone as odd? Shouldn't that be the other way around? Isn't Gary like 50 years old and Dwight 45? Dwight can't be that old can he? Gary is 38 and Dwight is 42 actually.