The U.S. electric power sector is on the cusp of a massive transition driven by rising electricity demand, evolving policy, economic uncertainty, and environmental imperatives. This shift demands a rethinking of how the grid is planned and operated, including new approaches to investment, innovation incentives, and understanding the reliability, resilience, economic, and social impacts of competing solutions. Yet, detailed modeling tools to evaluate these outcomes remain limited, particularly in their ability to support decisions that enhance reliability and affordability while reducing environmental harms. The EARNEST Consortium aims to fill that gap by building open-source, stakeholder-informed tools for next-generation grid planning. In this talk, we will outline the goals for the projects and highlight the key research findings and decision tools developed to date, namely in the realm of capacity and transmission decision-making for U.S. states.