Businesses often have strategic visions for the future of a product space; however, identifying and building toward preferable futures is a daunting task, especially when designing for complex systems, e.g., Digital advertising platforms that include multiple complex interfaces and internal organizational structures. Moreover, because businesses need to iterate on products quickly, often in a reactive manner, many businesses, and consequently researchers, struggle to go beyond short-term needs to tackle long-term solutions; that is, they mostly react to immediate needs and changes rather than taking a proactive strategic approach towards building a favorable future. Speculative design as a methodology to support proactive strategic thinking helps set a pathway to explore a variety of future states with participants, in our case business owners. It does so by designing immersive and impactful experiments for participants that draws insight from well-researched forecast of the probable future, as viewed from today but also more open-form future possibilities, that rely on speculative and fantastical prompts (e.g., science fiction, modern art, fantastical scenarios etc) to generate reflection and dialogue. In this paper, we will present different variations of speculative design implementations at Facebook that allowed us to explore different potential futures of digital advertising. In addition to discussing this research approach, which was novel to this space, we have included retrospective thoughts and best practices that emerged among our product design teams as they reflected on their participation in this work. We hope that our lessons learned can benefit the research community, by broadening the strategic impact of research to design products and services that better anticipate future user needs and identify potential risks early in the process. Article citation: 2021 EPIC Proceedings pp 190–207, ISSN 1559-8918, https://www.epicpeople.org/epic