A lawn maintenance vehicle includes an adjustable seat assembly, wherein the seat assembly is rotatable relative to a frame of the vehicle when the vehicle is operated on a sloped surface. The seat assembly is rotatable in order to maintain the operator in a substantially vertical seated alignment while operating the vehicle on a sloped surface. The seat assembly is also rotatable when the vehicle is in a zero-turn or tight-turn maneuver, wherein the seat is rotated toward the center of turning radius to offset the centrifugal forces experienced by the operator during such a maneuver.