We discuss how a generic multi-period optimization based decision support system (DSS) can be used for strategic and operational planning in a company with five fundamental elements, namely, Materials, Facilities, Activities, Times and Storage-Areas. This DSS which optimizes the company's activities over multiple-time horizon, having a multi-material, multi-facility, multi-activity system, requires little or no managerial knowledge of optimization techniques. This is the first reported attempt of an optimization based DSS in an integrated steel company in the USA with real world data. The result demonstrates significant profit and revenue improvement potential.