you might have varied themes, such as the 'state of the art' in alternative silver processes, or toning, say - and have a bunch of practitioners doing interesting work talking about their work. The number of compelling concepts you could come up with are as unlimited as your imagination. Certainly, the community here would be more than willing to help out - and, I'd imagine, the more involved you get such communities with the planning and execution of it - the more seats you'd be able to fill as well... it seems to me it can be as big as you want to commit to. If you ever want to engage this idea, please let us know.
Bingo! I agree with Jonathan. Variety is the best way to get lots of people interested. In PPF, not many are interested in marketing, (I'd say about half or less) but many are interested in different ways of pursueing their photography, their craft.
The first Silver Conference had such variety. The only common demoninator was of course Black and White photography. I would wish that Color was included in someway. But that's my wish and I understand that Ilford is one of the major sponsors but so is Calumet.