The aim of this paper is to present a modified version of GAM (M-GAM) which should showthat the results gained by using this version are more accurate and realistic. The modification is based on theinclusion of tourists and their opinion regarding the importance of indicators in the assessment process. Theassessment was done by using both versions of GAM and the results were compared and analyzed afterwards.Both assessment methods were applied on the Lazar Canyon area located in eastern Serbia, a territory whichpossesses a large concentration of geosites on a relatively small surface area and it has great potential forgeotourism development. The study revealed that the inclusion of tourists in the assessment process can havecrucial impact on the final results. By introducing the importance factor in the modified model we were able topoint out those values which are of paramount importance for tourists. This can be rather useful in theimprovement and planning of tourism activities as it exactly shows which of the lower values should receivethe most attention in the future based on their significance for tourists.