Not only should the levels of communication be clear, but it is critical everyone is aware of the job functions of those they are working with. Knowing who is responsible for what areas will allow your communication to be direct and effective. Too often I have seen an e-mail bounce between 3 or 4 different people before it actually gets to the person with the answer. This is incredibly inefficient and often results in a lack of correct information for those at the bottom. The simplest way to resolve this issue is a clear organizational chart, that includes job function.
The second feature I believe is critical for successful communication, is ensuring it is clear who has the power to make a decision. For example, if you have client or customer facing roles for your event that are fielding questions, what are they able to do to resolve issues for them? What can they offer to ensure that the client or customer is satisfied. Knowing this makes it easy for these customer facing roles to make quick decisions that don't leave the customer or client feeling ignored as your employee is trying to get permission to offer something.
Keeping these channels clear and delegating power is an easy way to ensure time is spent efficiently to create the best results while preventing people who are focusing on the big picture issues from getting bogged down by the smaller issues.
