We have developed a data visualization interface that facilitates a design by shopping paradigm, allowing a decision-maker to form a preference by viewing a rich set of good designs and use this preference to choose an optimal design. Design automation has allowed us to implement this paradigm, since a large number of designs can be synthesized in a short period of time. The interface allows users to visualize complex design spaces by using multidimensional visualization techniques that include glyph plots, scattermatrices, and brushing. As is common with data mining tools, the user can arbitrarily assign variables to glyph attributes and specify upper and lower bounds to performance variables. Additionally, to help shape a decisionmaker's preferences, preference shading to visualize a user's preference structure, along with algorithms to visualize the Pareto frontier, were incorporated into the interface. Use of the interface is demonstrated through two example applications.