I am participating now in a Webinar sponsored by the American Planning Association on ethics, which is required for continuing membership in the American Institute of Certified Planners (AICP). Excellent session.
The following rules are taken from the American Institute of Certified Planners Ethical Principles in Planning. These principles are well thought out and reasonable.
The only items I would add would be that the Planner should be a leader. She or he should figure out the future needs of the community, and effectively communicate those needs to the City leadership. The planner should also search for the Win / Win.
The Economic Development Director is sometimes also the City Planner wearing two hats. The Economic Development Director is also often not a city planner. The ethical principles in planning outlined by AICP should be followed by an Economic Development professional.