G protein-coupled receptors (GPCRs) are integral membrane proteins critical to a variety of signaling tasks. Roughly one fourth of all drugs target GPCRs, underscoring their biomedical importance. Rhodopsin, the dim-light receptor in the mammalian vision system, has been studied extensively by both experimental and computational means. However, much remains to be learned about its mechanism of action. For this reason, we used a variety of molecular modeling techniques to understand the relationship between structure, dynamics, and environment in controlling rhodopsin's function. In this presentation, I will discuss three different calculations: 1) all-atom molecular dynamics simulations of rhodopsin and opsin intended to illustrate the role of allostery in rhodopsin function; 2) coarse-grained simulations of rhodopsin that clarify the role of membrane composition in modulating rhodopsin function; 3) simulations using a structure-based potential to describe the activation mechanisms of rhodopsin and beta-2-adrenergic receptor. Taken together, these projects show the value of computational methods in generating new insights.