This paper presents two contributions: (i) a system architecture capable of staging platform-independent choreographies within different virtual worlds, and (ii) an ontology-based solution for capturing and representing multi-user choreographies with reduced time/effort. We argue that choreographies for virtual worlds should be clearly separated from the technical characteristics of their execution in virtual world technological platforms. Due to the heterogeneity of the various virtual worlds and their domain requirements, we propose exploiting the modularity, generality, and granularity dimensions of ontologies to simplify and empower the choreography modeling capabilities. Instead of a unique ontology, several ontologies with different levels of generality and granularity can be progressively combined to support the modeling requirements of a given choreography. Because these ontologies are aligned with the ontology of each specific virtual world platform, the mapping and transformation between the core ontology is simplified and automated, thus reducing the development and time-to-market.