From an interview between Tom Spurgeon and Mark Waid, talking about working as an editor at DC Comics under executive editor Dick Giordano;
I was actually offered this job about four or five years ago at DC. Dan for a while wanted to move on to a different part of the company. He invited me to take the job, and I went up there and had serious negotiations. We talked about it. Unfortunately, it fell through on some counts that had nothing to do with me. For that week I thought that was the next step of my career? Tom, I felt ten feet tall every day. I really felt like, “Man, this is it. I’ve been watching the Yankees since I was six and I’m finally on the mound, pitching.” Not because I felt, “Everything is broke and I have to fix it.” Or “Oh boy, I get to play with all of these fabulous toys.” It wasn’t quite that simple. It was more of a sense of having gotten to a point where I’m almost as good a teacher as I am a writer. I yearn to be able to work with younger creators and pass along what I know. That doesn’t mean I have all the right answers, and doesn’t mean I’m necessarily going to teach the right things. I’m going to be wrong in a lot of my philosophy, too. That’s just the way it is. I enjoy that part of the job. I would have enjoyed the idea of sitting down with that stable of characters and that stable of writers and having a meaningful dialogue about here’s what I think you’re trying to do, and here’s how I might be able to help you accomplish that. I think I have enough experience under my belt that you can take my suggestions seriously.
A DC Comics run by Mark Waid would have been an interesting beast. He might have let himself write Superman as a treat. Grant Morrison would probably got more of his pitches though. And there would probably have been less JMS.