Man, it's hard to beat having gotten to play Superman. But where do you go from there? Aren't careers supposed to culminate in a role like that? And because I'm a big fat geek, as long as there's stuff I'm excited about - and isn't that really the definition of geek? - there'll always be roles I'd love to play.
It usually starts with the director and any other creatives who may be involved at the start. It's a collaboration. I bring what I have naturally and, hopefully, what they cast me for, and then we start playing and tweaking until we have what they feel's right. It helps to have some artwork to inspire me, but I don't always get that luxury.
As far as actors who pop up again and again in Japanese dubs, and because they're really good actors, people like Steve Bloom, not only in 'Cowboy Bebop,' but also he's sort of the de-facto Wolverine. If you're doing an animated Wolverine anything, Marvel usually just goes to Steve first because he's recognized as that voice.
Sometimes I become attached to a character because I've gotten to explore him for so long, like in the case of Ben, but sometimes I fall in love with a throwaway character who exists for only one scene in a video game like The Drunken Villager in 'Diablo III' or Sandal in 'Dragon Age.'