The aim of this paper is to develop a unifying framework for discussing dynamics and thermodynamics of externally driven fluids. Since the levels on which the driving force is defined and the dynamics is discussed are often different, the analysis is conducted and interpreted in the context of multilevel realizations (developed in this paper) of the unifying framework provided by generalized Hamiltonian structures. The framework is based on the experimentally established fact of the existence of reduced descriptions of both isolated and driven macroscopic systems. Thermodynamics of externally unforced as well as driven complex fluids arise from the general concept of thermodynamics introduced in the unifying framework.