Abstract: Direct detection experiments are making tremendous progress in measuring increasingly small energy depositions. As this energy threshold decreases, different excitation channels, such as nuclear recoil, electron transitions, and single phonon excitations, become available. We present a unified theoretical framework for computing direct detection rates via these channels, and expand on previous results in the literature. We derive the in-medium screening effects for a generic model from first principles, incorporate general spin-independent couplings and Umklapp processes in single phonon excitations, and give an example of a simple, bulk, anisotropic target exhibiting daily modulation in electron transitions. We then use this framework to carry out a comparative study of the reach for two benchmark dark matter models with 24 target materials across all these channels, and highlight the target properties which should be optimized in order maximize the reach.