Nowadays, analysis of land-use suitability requires consideration of variety of criteria including not only natural/physical capacity of a land unit but also socio-economic and environmental impact implications. This chapter suggests an approach instead of typical synthesis and land-use suitability assessment methods that is used in the urban and regional planning. Using the decision support systems with AHP and GIS, a participative, GIS-supported, different, new, flexible, and soft approach is proposed for land-use suitability assessment of cities and regions in particular. The chapter presents a technique integrating SWOT-CATWOE analysis, the Delphi and Inquiry Technique, the Analytical Hierarchy Process (AHP), and a Geographic Information System (GIS) to evaluate the land-use suitability for cities. By the help of this study, settlement suitability analyses have been achieved according to the socio-economic and infrastructure, environmental or physical thresholds of the settlement, and this integration could benefit urban planners and decision makers. The proposed method begins with the identification of settlement requirements, followed by the derivation of settlement evaluation criteria with SWOT-CATWOE analysis and the Delphi and Inquiry Technique. Then, pairwise comparisons (PC matrices) are formed between each pair of settlement criteria. The AHP is used to measure the relative importance or weight of each settlement criterion. This chapter has intended a theoretical and scientific base for an AHP and GIS combination with decision support systems. Thus, when land-use suitability assessment has taken as this combination of decision support systems, AHP and GIS, more realistic, more accurate, and applicable results emerge.