Panels can be tricky.
Rebecca has been asked to moderate a number of panels, so I ask her to pass on some hints she has learned over the years. Interview a representative sample of the people most likely to attend. Choose your panelists carefully. I have sometimes called prospective panelists asking the question above to see how articulate they are. If they have interesting thoughts on the topic and can express them clearly, I will call them back and ask them to be panelists.