He shouldn't be used for a while. Ra's al Ghul's natural role is as the Bigger Bad Beyond, within Batman's world. I would love the League of Assassins to be hinted at occasionally, just so that a picture can emerge of how insidious it is. When The Daemon's Head actually appears, it should have a sense of catastrophe about it.
Also- a small matter- I would like the ethnic ambiguity of the al Ghul's to be restored. I would love to hear Ra's and Talia talk to each other in Arabic, Coptic or any other number of middle easter/central asian languages.
As for an actor, I would plump for Ben Cross, who I think is a seriously underrated (and underused) actor. He is another white European but, like Christopher Lee, he could probably play anything. And he has the killer al' Ghul cheekbones.
Oh, and Lazarus pits. Gotta have 'em.
*kicks Dobson in the chuddies*