Erik Davis’ Experience Design And the Design of Experience is the single best piece I’ve read on the subject.
Not only does he offer a sublime definition of experience:
“…let’s just think of human experience as the phenomenal unfolding of awareness in real time”
…but he also touches on some powerful, related topics such as recreational drug use, spirituality and also scary shit like the manipulation of desire for the purpose of advertising.
Additionally, much of what he writes suggests an increasing need for Design Ethicists—a topic in which I’m surprised to find myself very interested.