Reagan looked pretty good. I think Bush will look pretty good because they weren't/aren't consumed by evil.
Well, Clinton DID age from 46-54 during his Presidency, those years start to show on everyone I've known. I'm sure the job had something to do with it, but it's hardly all.
I agree that Cheney won't and probably shouldn't run, but he's so calm and knowledgable, I don't think the job would kill him.