In the talk we present the rationale for the GiantSteps project, a collaborative effort by music information retrieval (MIR) researchers and creative music practitioners, funded by the European Union. The project aims to create musical tools and instruments that provide users with intuitive and meaningful interfaces to complex selections of samples and musical data though expert agents, music analysis algorithms and new interfaces. We outline the overall concept of the project and the methodological framework for the user involvement and suggest a number of ways that we might be able to find new ways to support musicians in imagining future instruments for creative musical expression and find new ways to creatively exploit vast collections of music samples.