In order to understand different offloading options in realistic network scenarios from a theoretical viewpoint, we develop in this paper a generic analytical framework for providing estimated gains of specific offloading regime. Simple closed-form approximations are derived to provide analytical evaluations in terms of offloading efficiency. By characterizing different offloading options in various priorities, we further propose a hierarchical mobile data offloading scheme. Such scheme allows for dynamic offloading onto alternative options, with particular concerns on priorities inherently associated to various offloading options. Numerical results further prove achievable performance gains with the enhanced mobile data offloading scheme.