Events should be organized (prepared in advance) to maximize social opportunities: Who do I want to meet? What am I looking for? … there are lessons to be learned from social networks (LinkedIn …).
Speakers : nice (or not) background noise. We don’t need to see the guys (& ladies) live. We can find their talks on YouTube, TED, … less expensive, less time consuming …
Venues : have to provide big lobbies, many small rooms, lawns, a number of bars, etc. Places to meet, take a nap, read, etc.
Business model for event organizers : I’d be ready to pay per new contact :-)