Tourism externalities, such as gentrification, over-tourism, and the Bilbao effect, are key concerns in contemporary urban and regional planning. A wide range of approaches for measuring sustainable tourism have been developed, highlighting the challenges associated with comparing performance and outcomes across different destinations and scales. To address these issues, the paper proposes a spatially explicit taxonomic classification of the tourism ecosystem structure to a relevant set of spatial variables that characterize the supply of a specialized tourism value chain. The study identifies, evaluates, and compares specialized tourism destinations areas, applying the balanced supply index to produce a high-resolution cultural tourism map. The approach strengthens electronic planning by integrating geospatial data into a robust analytical framework, aiding sustainable tourism management and regional planning. It supports place-specific policy design and promotes adaptive, data-driven urban and regional electronic planning.