I've always thought Gregory Peck was the perfect Bruce Wayne, much more so than Christian Bale. Right height, physique, hair color (hot topic nowadays!), ruggedly handsome face (vs. Cary Grant who was suavely handsome). But most of all, the way he carried himself with such dignity and substance.
As for Selina, I've always pictured Ava Gardner in that role, much more so than Audrey Hepburn who I think is too sweet and innocent for it.