We employ the properties of metamaterials to tailor the modes of metamaterial-dielectric waveguides operating at optical frequencies. We survey the effects of three-dimensional isotropic metamaterial structural parameters on the refractive index of metamaterials and on the hybrid modes in slab metamaterial-dielectric waveguides. Hybrid modes refer to hybrid ordinary-surface plasmon polariton modes in the waveguide structures. We investigate how robust metamaterials are to fluctuations in their structural parameters; specifically, we examine the effects of Gaussian errors on the metamaterials electromagnetic behavior. Our survey enables us to determine the allowable fluctuation limits and from this to identify appropriate unit-cell structure for further applications of metamaterials in waveguide technologies.