I think that the general theme of batman: a man using technology and will to enhance his abilities and power, has such a versatility that it could be used for stories set in numerous time period.
Specifically a batman movie set in the darkages or renaissance would be totally sweet. i remember a comic book that explored that theme ages ago. I think da vinci was batman's gadget guy
A renaissance batman movie would be sweet. batman vs the medici or something.
Also a batman in the future would be sweet, really exploring the possibilities of a techno batman suit

Indeed. The character fits pretty much any time and place, and he's universally identified with... And not least of all by anyone that's lost a parent.

Wayne gets shot back in time in the comics, and has to fight his way to the present, it's like a quantum leap meets batman but time traveler thing.

Plus there's alternate universe comics where batman is like a english chap who is chasing down a serial killer in foggy london town