This paper explores the spatial aspects of GIS-based multi-criteria evaluation. We provide a systematic account of geographically defined decision criteria based on three classes of spatial relations: location, proximity, and direction. We also discuss whether the evaluation score of a decision alternative should be directly influenced by neighbouring scores and outline a methodology for distance-based adjustment of evaluation scores. A home buyer case study is employed to demonstrate how spatial criteria can be included in a spatial decision support system and to investigate the effect of geographically adjusting the evaluation scores of decision alternatives. The case study demonstrates how spatial criteria can be presented to decision-makers and their effects be observed in the decision outcome. Further, the spatial adjustment of evaluation scores using the performance of neighbouring properties smoothes the distribution of scores across the study area and allows decision-makers to consider a location’s environment.