Reflection-absorption infrared spectroscopy (RAIRS) is used to compare and contrast the coordination, bonding, and configurational transitions for benzene and pyridine adsorbed on Pt{111} and Cu{110}. Benzene adsorbs on both surfaces with its molecular plane parallel to the surface. As a result, the out-of-plane CH bending mode is the only IR-active mode observed on each surface. On Cu{110} a single absorption band is seen at around 680 cm(-1), whereas on Pt{111} two bands are observed with frequencies of 900 and 830 cm(-1) and the latter splits at high coverages. The differences are attributed to the relative strengths of the interaction of benzene with the two surfaces and the occupation of 3-fold and 2-fold adsorption sites. The adsorption of pyridine also shows distinct differences on the two surfaces. On Cu{110}, pyridine initially adsorbs with its molecular axis perpendicular to the surface plane, with vibrational frequencies similar to those of the free molecule, On Pt{111} the orientation of the molecule is both coverage and temperature dependent. At 300 K an alpha-pyridyl species is formed, bound in an upright configuration. At 85 K the molecule initially adsorbs in a tilted geometry, and with increasing coverage undergoes a rotation about the C2 axis. Over the temperature range 140-250 K the pyridine molecules that are adsorbed intact are initially bound with their molecular planes parallel to the surface plane, and subsequently with increasing coverage show some tilting toward the surface normal. The degree of this depends on the surface coverage, which is itself temperature dependent. Additionally, over the temperature range between 200 and 260 K IR spectra show the presence of an alpha-pyridyl species with its molecular plane parallel to the surface. The alpha-pyridyl species shows vibrational frequencies which are distinct from those of adsorbed pyridine seen on both Cu{110} and Pt{111}.