An effective way to compare logic techniques, logic families, or cell libraries is by means of power (or area) versus delay plots, since the efficiency of achieving a particular delay is of crucial significance. In this paper we describe a method of producing an optimized power versus delay curve for a combinational circuit. We then describe a method for comparing the relative merits of a set of power versus delay curves for a circuit, each generated with a different cell library. Our results indicate that very few combinational functions need to be in a cell library, at most 11. The power-delay points achieved by Design Compiler from Synopsys using the state-of-the-art Artisan Sage-X library compare unfavorably to our approach. In terms of minimum energy-delay product, our approach is superior by 79% on average. Our approach yields the same delay points with a 107% savings in power consumption, on average. We also show that the specified VDD for a process technology should only be used for the absolute fastest implementations of a circuit.