Recent conferences have engaged professional event managers to assist with organising the events. They take care of the finer details around venue wrangling, speaker flights and hotel bookings, visa letters for the speakers who needed them, council permits if required, buses and venues for social events, agendas and minutes for committee meetings, and more.
Their expertise allows the committee to focus on higher-level decisions and communications, and having them assist from about six months before the conference onwards is recommended.
Stage Managers are essential to the smooth running of the event. There should be one focused on each stage at any given time (which means that having two people per stage is probably wise, so they can each take a break).
The role of the stage managers is to make sure speakers are prepared, and to keep them on track with time limits. This should be their only role for the conference - and if they need anything, it's recommended they call upon volunteers for assistance.
It is recommended that a band of volunteers is gathered to help manage the event across the days it takes place. These people should be directed by a Volunteer Manager.
Having volunteers as the first point of contact for many attendees reduces the load on organisers, who can then deal with the bigger picture issues, or even sit back and enjoy the event occasionally.