I agree with Xizor. When I hear Christopher Lee as a Star Wars actor, I see him as a diplomatic senator or governor who turns to the dark side, or tricks the high governmental prowess into thinking different than what's right. A dark jedi maybe, but he would be better as a Palpatine-like character. He and palpatine being a evil senator-duo would be pretty sweet.
Here's an interesting idea. Lee and Palpatine do behind the scenes planning on how to manipulate the senate to palpatines wishes. On the outside Lee would sometimes agree and sometimes disagree with the chancellor, sometimes he appears good and other times very evil. As we know eventual the clone wars blow up in Palpatines face. Lee could take the fall for him, the senator could also be the first to be put to death by the dark side lightning. Palpatine blaming Lee for anything and everything that went wrong for him in ep2.