This paper provides an overview of the optical properties of plasmonic nanoparticles, using gold nanowires as a model system. The properties were calculated using classical electrodynamics methods with bulk metal dielectric constants, as these methods provide a nearly quantitative description of nanoparticle optical response that can be used for particles with dimensions of a few nanometers to many hundreds of nanometers. The nanowire calculations are based on the finite-difference time-domain (FDTD) method in two dimensions, and we specifically consider the transmission of light through nanowire arrays, as this provides a simple nanomaterial construct which still displays the richness of optical phenomena that is found for more general nanostructures. The calculations show a number of features that are known for other nanostructures, including the red-shifting of plasmon resonances as wire spacing is decreased, and as particle aspect ratio is increased. In addition, the influence of dielectric coatings on the wires is examined, including factors which determine dielectric sensitiv. These results provide insight into what structures will be most effective for index of refraction sensing applications.