Ultrathin liquid films of three hexadecane isomers and of squalane physisorbed on a flat metal (Au(111)) surface have been studied by Monte Carlo and molecular dynamics simulations. Density oscillations arising from the layering of methyl and methylene groups on the surface are observed in all films. Branched molecules exhibit a decreased tendency to layer and an enhancement in the degree of interdigitation. Comparisons are made with recent surface force experiments and other simulation studies.