The Flory-Huggins interaction parameter, chi, is often used in the literature to describe the binary interactions of polymer blends, yet to what extent does this widespread analysis yield valuable thermodynamic insight? In this work we think critically about chi and creatively about alternatives. Making use of a simple lattice theory to model binary polymer mixtures, we follow a different, less ambiguous route and show connections between the microscopic characteristic parameters of a system and its macroscopic thermodynamic behavior. To this end we analyze experimental data, including results from neutron scattering experiments, cloud point curves, and pressure-volume-temperature (PVT) surfaces for a series of blends, including deuterated polystyrene/poly(tetramethyl bisphenol A polycarbonate) (dPS/TMPC), deuterated polystyrene/ poly(vinyl methyl ether) (dPS/PVME), polystyrene/polybutadiene (PS/PB), deuterated polystyrene/ poly(pmethylstyrene) (dPS/PpMS), polypropylene/ deuterated head-to-head polypropylene (PP/dhhPP), polystyrene/deuterated polystyrene (PS/dPS), polystyrene/polychlorostyrene (PS/PCS), deuterated poly(methylbutylene)/poly(ethylbutylene) (dPMB/PEB), and poly(ethylmethylsiloxane)/deuterated poly(dimethylsiloxane)(PEMS/dPDMS). We conclude by suggesting that there is a temperature-and concentration-independent parameter which may prove to be a more characteristic indicator of blend behavior than chi.