I will discuss the deep connections between design and implementation in two contexts. I will first discuss an attempt to design a touch interface for information visualization, and talk about how design was an integral part of the process. I will then turn to an analytics system we are developing called “Stat!”. Stat is designed from the ground-up as a big-data analytics system: it allows users to run computation on very large datasets and get results fast. Developing the system requires deep thinking about user requirements, design, and system implementation—and how decisions about each of these aspects affect the others.