Dave Winer posts a lot of insightful ideas about the future of conferences. My instincts are that a hybrid of approaches are what is required - a combination of common experiences (keynotes), structured communications (sessions), and adhocracy.
The closest I have seen come to this was the ApacheCon, which had a parallel hackathon running during most of the sessions. What the hackathon had was 802.11, power strips, tables, chairs, and a few whiteboards. In my experience, power strips are the most overlooked accessory by conference organizers.
I know many West Coasters that are just hitting their stride at midnight, so if you want to truly even the playing field, make the keynotes all happen at 7 a.m.. Las Vegas is also a great location in that nobody lives there, and everybody can get there easily.
I'm not a fan of speakers during eating. Eating is a wonderful opportunity to talk to the person next to you. Rooms with PC's or Mac's are so last century, these days most people bring their own internet access devices.