Large-scale second-order perturbation theory and couple-cluster theory calculations were performed on the Na+(ethylene) and Naf(benzene) complexes in an effort to estimate binding enthalpies in the complete basis set limit. The resulting best estimates are Delta H-0[Na+(ethylene)] = - 13.6 +/- 0.2 kcal/mol and Delta H-0[Na+ (benzene)] = -24.4 +/- 0.3 kcal/mol, which include small corrections for core/valence correlation effects. The former value can be compared to a measurement of -10.3 +/- 1.0 kcal/mol obtained from collision-induced dissociation, while the latter value is approximately midway between the two existing experimental values which differ by 6.5 kcal/mol.