Localization effects on the optical properties of GaAs_{1- x}Bi_x/GaAs single quantum wells (SQWs), with Bi contents ranging from x = 1.1% to 6.0%, are investigated using continuous-wave and time-resolved photoluminescence. The temperature- and excitation density dependence of the PL spectra are systematically studied, and the carrier recombination mechanisms are analyzed. At low temperatures, the time-integrated PL emission is dominated by the recombination of localized electron-hole pairs due to the varying content and clustering of Bi in the alloy. The extracted energy scales fluctuate tremendously when the Bi content is varied with a weak tendency to increase with Bi content. Relatively low energy scales are found for the SQW with x = 5.5%, which makes it a potential candidate for long-wavelength optoelectronic devices.