Let me first say that I am absolutely honored to get asked to speak anywhere. I love it. I don't really care how large the event is--if you put me in front of a curious audience and give me a topic I'm passionate about, I'll do my best to share what I've learned and try to inspire.
That being said, one of my least favorite things in the entire world is a panel prep call. I've probably been on at least two or three dozen by now and I've never ever felt like it was a good use of anyone's time. That is not to say that a panel shouldn't be organized beforehand--it absolutely should. In fact, most moderators don't take enough of a lead in quarterbacking a panel. That's why most of them suck. It's a free for all.
If you're going to do a panel, you should do the following:
1 - Draft a TEAM. A panel should represent a diversity of opinion and perspective. Four entrepreneurs who took VC money talking about fundraising does not constitute a team--that's a group of individuals. Give me an entrepreneur, a lawyer, an angel and a VC. Now there's a discussion with multiple angles, especially if you throw in a bootstrapper just to mix it up. The whole of your panel should be greater than the sum of the parts.
2 - Script both the questions AND the answers. You should know exactly what answers you're getting out of each person. Ideally, that's why you picked each person to begin with--because you know they're thoughtful on this specific topic. And please don't ask every person every question. Two answers per question from the panel are good enough--and it allows you to cover way more topics. Plus, you can bounce around the panel, keeping it lively, instead of going down the line.
3 - Dictate your goals to the panel. As the moderator, it's your show. Tell us what the audience wants and how you plan to inspire them. An email outlining this is fine. You should welcome feedback, but a group phonecall isn't going to magically produce a panel structure. At best, you'll get some insightful feedback that we could have supplied by email. At worst, we reenact the whole panel on the call. Plus, panel calls take up valuable daytime working hours, and untold cycles of scheduling emails. For every four person panel with a moderator, you suck up around two person-hours for every 20 mins of prep call when you include scheduling the call. If you multiply that times the entire conference industry, what's that doing to our economy? If the end result is that panels still suck, is it worth it?
How about we replace that time with two hours of moderator training? Moderating is terribly hard, but if we made people better at it, that training would last a lifetime. Panel quality would improve. Knowledge and wisdom would be transferred for efficiently and retained better. The intellectual dialogue of society would improve and we'd finally get around to solving the world's tough problems.
After that, you can all thank me for killing off panel prep calls.