We all know why Gotham is fundamentally a bad idea: it's a show dedicated to telling us everything about the Batman story before the Batman story gets interesting. A different version of this show, one dedicated to the idea of Gotham as a city and not simply the idea of setting up Batman, could be great.
Which is why the rumor of a Krypton show fills me with interest. According to Bleeding Cool David Goyer is working on a TV series set on Superman's doomed homeworld, and I think that's pretty great. The history of Krypton has been sparsely explored (John Byrne's The World of Krypton is one of the few in-depth looks at the planet pre-blowing up) and is open to lots of possibility. Ideally you wouldn't set the show five years before the destruction of the planet but rather set it at some random, old timey point in history, with the destruction fifty or a hundred years (or more) away. Make it a space opera adventure that uses the scifi trappings to tell a story that critiques and reflects our own world. It's essentially a tragedy, but one where you can lay the seeds of hope that will grow into Superman.
Of course with David Goyer attached many are hesitant. And I have a hard time believing it will be anything other than "T-Minus Ten Years To Explosion: The TV Show," but we can hope, right? A scifi show set on an alien world so like our own but fundamentally different, with just the slightest connections to comic book mythology.