This paper presents a design characterization of heterogeneous sensor networks with the goal of geolocation accuracy. It is assumed that the network exploits sensor management to conserve node power usage. We focus on bearings-only sensor networks consisting of acoustic and imaging modalities. Each available node modality is a bearings-only sensor of varying capability. The optimal mixture of modalities is discussed under the constraint of the overall network cost. Finally, simulations verify the theory and demonstrate design choices.