GIS is used by land managers and natural resource planners for understanding resource distribution and project planning, often by visually interpreting spatial data representing environmental or regulatory variables. Frequently many variables influence the decision making process, and modeling can improve results even with a small investment of time and effort. Presented are several grid-based GIS modeling projects including (1) land use optimization under environmental and regulatory constraints, (2) choosing a wetland mitigation site, and (3) predictive mapping of prehistoric cultural resource sites. As different as the applications are, each follows a similar process of problem conceptualization, implementation of a practical grid-based GIS model, and evaluation of results.