The efficiency of poly(vinyl chloride) (PVC) plasticization depends predominantly on the strength of PVC plasticizer interactions, which ultimately depends not only on the intrinsic physicochemical properties of the plasticizer but also those of the polymer. The aim of this work was to study the influence of the morphological properties of different PVC grades (two emulsion (with different K values) and one microsuspension grades) and of nonconventional greener plasticizers on the rheological/aging properties of PVC-based plastisols and on the thermal and plasticizer leaching properties of films obtained from those plastisols. Commercially available castor oil based CITROFOL AHII and GRINDSTED SOFT-N-SAFE were employed as plasticizers, and the phosphonium-based ionic liquid (trihexyl(tetradecyl)phosphonium bistriflamide ([P-6,P-46,P-14] [Tf2N] as a coplasticizer. Plastisols formulated with the conventional plasticizer di-isodecyl phthalate (DIDP) were also prepared for comparison. Obtained results showed that the highest shear stress and plastisol aging were observed for plastisols formulated using the lower molecular weight emulsion PVC grade (E70-PVC) and the conventional plasticizer DIDP. The E70-PVC systems formulated using DIDP and citrate-based plasticizer presented a pseudoplastic behavior, while all the other systems presented a Newtonian profile. Lower mixing enthalpies were also calculated for PVC/DIDP systems, indicating more favorable interactions for PVC/phthalate systems over nonconventional plasticizers. The incorporation of [P-6,P-6,P-6,P-14] [Tf2N] as a coplasticizer significantly decreased the enthalpy of mixing of all the prepared plastisols, showing that its presence in the formulations may favor PVC/plasticizer interactions. Moreover, PVC films obtained from plastisols formulated using this ionic liquid presented higher long-term thermal stability due to its negligible vapor pressure that avoids loss during usage.