The electronic band structure in polarized GaInN/GaN heterostructures is studied in photoluminescence excitation spectroscopy. Within multiple quantum well samples optimized for homogeneity, sets of narrow excitation maxima with full width at half maximum values of 10 and 25 meV (T approximate to 12 K) are identified and attributed to interband transitions involving excited quantized states of the quantum wells. A selective attenuation is achieved by variation of the detection energy. Those values are significantly smaller than the linewidth of the emission paths. Together with higher emission energies emphasized by higher excitation energies, this supports concepts where absorption and emission paths do not share the same broadening nor the same interband transition. The result of such well-resolved transition levels provides a basis for future detailed band-structure models.