In order to understand the evolution of high-redshift galaxies, it is important to accurately characterize the molecular gas that fuels their star formation. Access to the CO(1-0) line near the peak of the cosmic star formation rate density (z~2-3) at the Robert C. Byrd Green Bank Telescope and the Jansky Very Large Array has revealed a substantial reservoir of cold molecular gas in submillimeter-selected galaxies. These data present a more complicated picture of the molecular ISM in submillimeter galaxies than implied by previous analyses using only mid-J CO lines. However, it is possible that the galaxy-wide averages of the CO line ratios used to determine the molecular gas conditions hide spatial variation on sub-galactic scales, disguising the true excitation conditions. I will present recent results for several z>2 star-forming galaxies that illustrate how high spatial and spectral resolution mapping affects our characterization of the molecular ISM and enables analyses similar to those performed on low-redshift galaxies, like the resolved Schmidt-Kennicutt relation.