The main school of utilitarianism believes that we should increase happiness and decrease suffering. The presence of happiness and the absence of suffering is named utility. Under this system of ethics, conscious experience matters, but unconscious events don't.
Utilitarianism is a type of consequentialism. That is, utilitarians believe that doing the right thing will make the world a better place. What does not improve the world is not good, whatever people might say. Once it is established that happiness should be spread and suffering should be limited, what remains of ethics is no more or less than the greatest logistical challenge of all time.
There is an alternative definition of utility that is not focussed on conscious experience. This kind of utilitarian, a preference utilitarian, aims to satisfy people's preferences. Preference utilitarians only disagree with classical utilitarians about actions that will fulfil people's preferences without bringing them happiness or vise versa.