I've always really liked Al Franken, although as he's gotten more political and argumentative he's lost a bit of his charm. Oh well, I'll probably try to catch his radio show anyway, so long as it's streamed on the net. I have his White House correspondence dinner speeches from 1994 and 1996 and listen to them regularly. Not only are they funny, but they are brilliant examples of what you can do when you know and understand your audience.
But if it's serious news you're looking for, it's hard to find a better voice than Bob Edwards of NPR. Unfortunately, he won't be leading Morning Edition anymore. He'll still be around, and I'm sure NPR has chosen his successors wisely, but it just won't be the same.
As for what you can and cannot say on the radio (or other mass communication mediums), I'm always interested in what George Carlin has to say. My fondness for George Carlin goes beyond being a simple fan; it's more interesting to look past his humor and see the message within. If you can imagine George Carlin sitting down to hash out philosophy with the Dalai Lama, then you have an idea of the kind of worldly views that interest me.