I would take it as though most people are there to hear Brian Tracy and not so much for the networking. While I doubt it is a "no sales" zone event, you will probably find a the full spectrum: people who don't want to be sold all the way up to people who are trying to sell the shit out of everyone they meet. You aren't the first to think, 'Hey - if I go where the CEOs go, then I'll have a shot at pitching them directly!' so expect to see many doing what you are doing. As such, don't waste your time on them - they are your competition.

And unless your startup is somehow "For every CEO" (a la linkedin) then you need to find a way to know beforehand who to look for and which areas you want to focus on. What companies do you hope will be there? Ask around at the event and see if any of that company's employees are there. What areas are you wanting to sell into? Ask around for who is at the event in those areas and talk to them. Don't just waste time talking to CEOs; talk to CEOs in your target market.

And these are rhetorical questions; I'm not expecting you to answer them here :)