Love him or hate him, it looks like you are stuck with Clooney for at least two more Bat-films. For the record I think that Clooney is the most Batman-like in costume. However his Bruce Wayne fell quite short. In all fairness to he and Val Kilmer, they both had a poor Bat-director. As far as overall appeal, my money is still on Keaton. And believe me, when I heard he was awarded the role I was tempted to pass on the first movie all together. And I think that Warner Brothers felt most people might think that way too, look who got top billing! But as the date of the premiere approached, the idea of Keaton ("Mr. Batman" as he was being maligned at the time) as Batman began to grow on me. And I found that I did indeed love him in the role and looked forward to Batman Returns. Of course Nicholson was the ideal choice for the Joker and buzz is that he is keen to reprise the role (hopefully in World's Finest). I had long before the first Batman film cast Danny DeVito as the Penguin so I was thrilled that he got the role.
So for those of you who think that I prefer Clooney to Keaton, there you have it, I simply do not. But visually, in costume, as Batman, Clooney had the look. And speaking of early fan resistance to Keaton as Batman, and it was widespread, making the post-facto love of Keaton in the role (my own included) all the more ironic. Before its release almost everyone hated that he was going to don the mantle of the Dark Knight Detective. Afterward, and moreso in the wake of two subsequent Bat-actors, everyone pines for Keaton in the role. I bring this up in reference to the (rumored) unlikely choice to play Superman opposite Clooney's Batman in World's Finest, John Travolta. I think that if this is true, his casting would meet resistance that will rival that of Keaton's. I must admit I find him an unusual choice, but I think that his performance could grow on audiences the same way Keaton's did. My dream version of World's Finest, regardless of who plays Superman would be to pit the pair against Nicholson's Joker and Lex Luthor played by Christopher Walken!