Digital mapping tools, and the “map mashups” they enable, may facilitate new and richer discourses about salient planning issues, particularly among stakeholders without specific expertise in geospatial technologies (Batty et al., 2010). In October 2016, the authors hosted a day-long workshop for transport and land use planning decision-makers from public agencies and private practice in Perth, bringing together innovative digital mapping and discourse facilitation tools, in an interactive presentation laboratory. These included the Spatial Network Analysis for Multimodal Urban Transport Systems (SNAMUTS) tool, and several complimentary techniques operating at smaller spatial scales, with a final 35-year backcasting tranche to identify perceived implementation blocks.This paper describes and summarises the methodological approach, and by drawing on participant observation and feedback, reports key outcomes of the workshop. The extent to which contemporary map mashups and interactive presentation facilities may add value in planning decision-makingis explored. Our interest is whether the approach: deepens stakeholder’s understanding of the complexity and contextual dimensions of futures planning; improves transdisciplinary stakeholder communication about common planning challenges; and, whether it mobilises tacit knowledge relevant for these tasks.Through experimental testing, many challenges highlighted in the literature became evident. There was also some difficulty among participants in the ability to engage in intertemporal decision making. Employing map mashup techniques in planning contexts to greatest effectiveness must include acknowledging the experimental nature of the processes and providing participants with opportunities to express general insights separately to specifically structured PSS tool input.