We present the results of three applications of using resolved stellar populations to derive star formation histories (SFHs) of regions in the nearby spiral galaxies M81 and NGC 300. We use data from the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST) and compare observed color-magnitude diagrams (CMDs) with synthetic CMDs from stellar evolution models to find the best-fitting combination of stellar ages and metallicities. In the outer disk of M81, we probe the stellar populations of small regions which are UV-bright but Halpha-faint as well as HII regions. We determine that the HII regions contain more massive stars than the other regions and are therefore consistent with being at least a few Myr younger; however, we cannot rule out a truncated initial mass function as an explanation for the differences between these regions. Our data for NGC 300 cover the location of an unusual optical transient, NGC 300 OT2008-1, which has been speculated to represent a new class of objects. Despite the lack of an optical precursor for this object, we infer the mass of the progenitor by deriving the SFH from the stars surrounding the transient location, under the assumption that since most stars form in clusters, the population should be coeval. We find a star formation event of age 8--13 Myr and determine that the progenitor should be a star which has recently turned off the main sequence, of mass 12-17 M⊙ . Expanding our view of NGC 300 to a radial strip of the disk from the center to 5.4 kpc, we divide the galaxy into radial bins and derive the SFH at each location. We find that the percentage of young stars in the outer regions is considerably greater than in the inner regions, but the slope of the surface density of the disk increases only slightly with time.