Most large development projects suffer overruns and delays, despite substantial effort spent on systems tracking risks and projecting performance.  Managers have an especially difficult time making big decisions such as major project re-plans.  Typical project management systems have key blind spots that limit their value for comprehensive decisions.  Most project management tools are blind to project dynamics – variations in productivity and quality over time under different conditions.  System Dynamics models have been used to address this weakness and capture project dynamics, but typically these models have their own blind spots as they omit key details.  With many pressing decisions and little time, managers rely on intuition to supplement the limitations of management tools.  The combination of little time for major decisions, limited tools, and unreliable intuition is a key contributor to the poor results often achieved on major projects.  This paper offers perspective on the challenges of making major decisions and describes a case using an integrated management tool -- a System Dynamics model linked to a database of project details.  This management system was used to restructure a multi-billion dollar development program with detail and rigor – examining dozens of different options, sensitivities, and leverage points in one month.