It's also a simple formula: find an expert in the field who's also a halfway decent host, then invite guests who work in the professional and balance their biases against each other.
Diane Rehm, for all her awards, has an awful tendency to cut people off in ways that destroy clarity. Things like letting someone give "on one hand..." and cutting them off as they say "but on the other hand...", so that only half their opinion gets aired.
On the "more technical" side, Science Friday really needs a host who understands something about science. Flatow's digested 'restatements' tend to be flatly wrong, and he's often two or three laps behind what an interested layman would pick up. I can understand going slowly in the name of accessibility, but he sort of forfeits that right by arriving at completely inaccurate final summaries.
It's not bad overall, but there's an aggravating tendency for the interviewers to 'participate' when they're not really qualified to have a dialogue instead of simply offering prompts.
Tom Ashbrook (On Point) does this especially egregiously. Some of his simplistic (or biased) "So what you're saying is..." moments make me cringe.
I realize it's a call in show, but jesus, there isn't anyone out there with a less obvious liberal bias / more technical background who's interested in the job?
Let callers or interviewees make their points fairly, then debate them. Rhetorically dancing around the topics with the advantage of being the host just makes me feel like I'm listening to Bill O'Reilly. (Ugh)