Density-functional theory is applied to study gas-liquid nucleation in binary mixtures consisting of Lennard-Jones atoms with hard-spherical cores (monomers) and bonded Lennard-Jones atoms of two (dimers) or three (trimers) hard spheres. Mixtures with and without amphiphiles are compared. In amphiphilic systems mutual enhancement of nucleation is observed regardless of reduced total interaction between the molecules. Monomer-dimer and monomer-trimer mixtures are compared. Increased chain length is shown to result in stronger enhancement of nucleation. Layered structures are shown to form in large critical clusters at certain vapor activities. The nucleation behavior of the amphiphilic systems resembles qualitatively the experimental observations of water-n-alcohol mixtures.