Integrated resource planning (IRP) has been widely used in the US for over twenty years. Although some state IRP rules have remained unchanged since they were first implemented, other states have amended, repealed, and in some cases reinstated their IRP rules. Recently amended IRP rules often reflect current concerns in the electric industry, e.g., fuel costs and volatility, the effects of power generation on air and water, issues of national security, electricity market conditions, and climate change, as well as individual state concerns. There are, however, certain subject-matter areas that are essential to resource planning on which state regulations are usually silent. This paper provides utilities, commissions, and legislatures with guidance on these subject-matter areas. It summarizes three recent utility IRPs, in an effort to determine both best practices in integrated resource planning and ways in which utilities can improve their planning processes and outcomes. The paper then presents a series of recommendations, developed from these examples, for integrated resource planning and its resulting plans.