The polarity of the ionic liquids [N-4111][Tf2N], [N-4441][Tf2N], and [choline][Tf2N], as well as their binary mixtures with ethanol has been investigated using solvatochromic dyes and expressed in terms of the Reichardt parameter, E-T(N), and the Kamlet-Taft parameters (pi*, alpha, and beta), at 298.15 K. The synergetic behavior revealed essentially by the ethanol + [N-4441][Tf2N] system for the acidity of the solvent shows the potential importance of this solvent media for some chemical applications. Even though the preferential solvation model of Bosch and co-workers has been applied with some statistical success to the whole composition range of EtOH + [N-4111][Tf2N] and EtOH + [N-4111][Tf2N] binary mixtures, the interpretation of the results is somehow difficult due to the competition of molecular interactions in the evaluation of transition energies for the pairs: dye-solvent (dye-cation and/or dye-anion, dye-EtOH, dye-complex entity) and cation-anion, depending on the composition range. Different patterns of solvent polarity behavior are shown along the entire ionic liquid (IL) composition.