The photoelectron spectra obtained following two-photon resonant, three-photon ionization of atomic iodine via a number of Rydberg states are presented. Photoelectron spectra obtained via the ${(}^{3}$${\mathrm{P}}_{2}$)np${[1]}_{1/2}$ levels and via the ${(\mathrm{}}^{3}$${P}_{0}$)4f${[3]}_{5/2}$ level demonstrate the production of state-selected ${\mathrm{I}}^{+}$ ${\mathrm{}}^{3}$${\mathrm{P}}_{2}$ and $^{3}\mathrm{P}_{0}$ ions, respectively, with \ensuremath{\sim}85% efficiency. Photoelectron spectra obtained via the ${(}^{3}$${\mathrm{P}}_{2}$)nf${[3]}_{5/2}$ levels show the effect of a perturbation by the ${(}^{3}$${\mathrm{P}}_{0}$)4f${[3]}_{5/2}$ level, as both ${\mathrm{I}}^{+}$ ${\mathrm{}}^{3}$${\mathrm{P}}_{2}$ and $^{3}\mathrm{P}_{0}$ are observed. The relative magnitudes of the $^{3}\mathrm{P}_{2}$ and $^{3}\mathrm{P}_{0}$ photoelectron peaks are shown to be strongly dependent on the relative magnitudes of the ${(}^{3}$${\mathrm{P}}_{2}$)nf${[3]}_{5/2}$ and ${(\mathrm{}}^{3}$${P}_{0}$)4f${[3]}_{5/2}$ photoionization matrix elements. Two additional processes are observed in the photoelectron spectra. These correspond to fluorescence of the resonant intermediate level to lower-lying levels, followed by ionization of those levels, and to energy transfer from ${\mathrm{I}}^{\mathrm{*}}$ ${\mathrm{}}^{2}$${\mathrm{P}}_{1/2}$ atoms to Rydberg atoms, resulting in ionization of the latter.