The widespread use of laser additive manufacturing processes for aerospace components will ultimately depend on the ability to predict and control the microstructure and resulting mechanical properties of the deposit. To this end, the focus of this work is the development of simulation-based methods for relating laser deposition process variables (laser power and velocity) to resulting microstructure (grain size and morphology) in both small-scale (LENS) and large-scale (industrial) processes. The approach employs the well-known Rosenthal solution for a moving point heat source traversing an infinite substrate. Cooling rates and thermal gradients (the key parameters controlling microstructure) at the onset of solidification are numerically extracted from the Rosenthal solution throughout the depth of the melt pool, and dimensionless process maps are presented for both 2-D and 3-D half-spaces. Results for both small-scale (LENS) and large-scale (higher power) processes are plotted on solidification maps for predicting trends in grain morphology for laser-deposited Ti-6Al-4V. Although the Rosenthal results neglect temperature-dependent properties and latent heat effects, a comparison with FEM results over a range of process variables suggests that they can provide reasonable estimates of trends in solidification microstructure. Finally, results from 3-D cellular automaton solidification modeling are used to provide direct predictions of solidification microstructure in Ti-6Al-4V, and results are compared to both the Rosenthal predictions and experimental observations. The results of this work suggest that changes in process variables could potentially result in a grading of the microstructure (both grain size and morphology) throughout the depth of the deposit, and that the size-scale of the laser deposition process is important.