As the planning process becomes more complex and turbulent and as the process moves from being rational to being more collaborative, new advanced tools are required to cope with the evolving challenges arise from involving diverse stakeholders with conflicting interests during different phases of the planning. This paper aims mainly to propose a conceptual framework for a Planning Support System (PSS) that combines the analytical capabilities of the Integrated Landuse and Transportation Models (ILUTMs), from one side, and the visualization and data presentation capabilities of the Geographic Information Systems (GIS), from the other side. The paper starts with a discussion of the planning process and reviews some of the available ILUTMs in addition to the enhancements that can be gained when they are integrated with GIS. In the following section, a broad review of the available planning support systems (PSS), their components, and their characteristics are introduced. In the next section, a general framework for a proposed PSS consisting of GIS and ILUTMs in addition to other components is introduced. Finally, the paper concludes with suggestions for the further work on the proposed framework and some of the expected challenges and limitations.