Since i don't know much about how the USA chanels work as i'm not from the USA i only have an idea of how it should be like.
I wouldn't like it to go to AMC because from what i heard they're allways cutting the budget of their most successful show, now, i wouldn't expect big car chases but in least i would like a budget big enough for a Batman vs SWAT team episode like in Year One, and Chuck's Season 4 finale ofered an interesting idea of how Batman's Motorcycle could work with a small budget.
I don't think the show should go with a main villain for each season like Buffy, but a season long story arc would be interesting, like for example, as season 1 covers Batman's Year One the season long story arc could be the Police corruption, the gangs with Falcone on it's center and James Gordon rising inside the Gotham PD.
If there was ever to be a season 2 it's story arc could be that of The Long Halloween, with the Holliday Killer revealed in the end. As for super villain, they would be recurrying foes and they could unexpectadly appear in normal crime episodes.
I think most villain could be easily used, Batman: The Animated Series had a selection of episodes that could be used as inspiration of how the villains could work with a small budget: Mr. Freexe's Heart of Ice, Poison Ivy's Pretty Poison, and many other examples, i think that the trickiest one would be Man-Bat because Flight fights like that would be really difficult to pull of on a tv budget.
One way to make WB accept the show running alongside the films is that as the next films may be reboots without origin stories the show can serve as a sort of Prequel to the film series, the TV show can also gather some interest for the films and make more people watch it