(a) Encourage imaginative design by permitting greater flexibility in zoning requirements than is generally permitted by other chapters of this title;

(b) Preserve or create environmental amenities superior to those generally found in conventional development;

(c) Encourage comprehensive planning of large industrial sites in order to create a park-like environment;

(d) Preserve to the greatest possible extent the natural characteristics of the land, including topography, natural vegetation, waterways, views, etc.;

(e) Provide for maximum efficiency in the layout of streets, utility networks, open space, landscaping requirements and other public improvements.