One of the best things about reading comic books, when you're a kid or an adult, is watching the characters cross-over. What happens in one book affects the other, and these shows are so tightly knit that it feels like one giant show.
Besides Spiderman and Batman, 'The Flash' has, hands down, the best villains. You could do a TV show about The Rogues, and there's enough depth and interest and oddly honor amongst those characters that I think people will watch that show.