This invention is generally related to using treatment fluids having additives that modify rheological characteristics. Some embodiments of the present invention provide methods of using treatment fluids comprising an aqueous fluid and an associative polymer additive, wherein the associative polymer additive increases the PV of the treatment fluid by more than at least 50% and wherein the associative polymer additive increases the yield point by no more than about 30% of the corresponding increase in the PV relative to a treatment fluid without the associative polymer additive in a portion of a subterranean formation.