I guess luckily for me, he was a little before my time.
I vaguely remember the Dick Cavett Show. He ripped off Merv Griffin's set design.
Cavett was a whiny liberal wimp on his show (as he still is), but he did have O'Neill on to debate Kerry. That's better than anyone else did.
He also did some great one on one interviews with older and half forgotten greats. He did some absolutely priceless stuff with Groucho Marx on his show, for example, that made it worthwhile to watch.