Coarse-grained, implicit solvent molecular dynamics simulations utilizing potentials derived from explicit atomistic simulations have been employed to understand the behavior of nanoparticles (C60 fullerenes and infinite (16,0) single-walled carbon nanotubes (SWNT) ) with tethered (grafted) poly-ethylene oxide (PEO) chains attached. The innate repulsive nature of the PEO-PEO interactions, coupled with the adsorptive nature of the PEO-nanoparticle interactions provide an ideal test bed for trying to understand the complexity of enthalpy/entropy competition in self-assembly processes. For moderate tethering (N=1-6) on the C60 particles, assembly is found to universally occur, even for systems with large chain tethers, due to the ability of the adsorption interaction to significantly lower the overall free energy of the system. The overall shape of the assembled clusters is a strong function of the tethered geometry, with cluster size controlled by both chain length and (secondarily) geometry. A unique ‘hugging' interaction is noted for symmetrically tethered chains which allows for association despite the uniform distribution of polymer on the surface of the nanoparticle, allowing for the formation of linear particle clusters. The SWNT system exhibits an analogue of this ‘hugging' behavior which, through control of chain length and grafting density along the tube, presents the opportunity for formation of nanotube ‘rafts' with controlled tube spacing.