Results from the present physics, materials, and blanket research and development programs are combined with physics and engineering design constraints to characterize candidate tokamak demonstration plant (DEMO) designs. Blanket designs based on the principal structural materials, breeding materials, and coolants being developed for the DEMO were adapted from the literature. Neutron flux and activation calculations were performed, and several radioactive waste disposal indexes were evaluated for each design. Of the primary low-activation structural materials under development in the United States, it appears that vanadium and ferritic steel alloys and possibly silicon carbide could lead to DEMO designs that could satisfy realistic low-level waste (LLW) criteria, provided that impurities can be controlled within plausible limits. Allowable LLW concentrations are established for the limiting alloying and impurity elements. All breeding materials and neutron multipliers considered meet the ELW criterion.