Interestingly Roberto Assagioli makes a case that Maslow's hierarchy of human needs is useful beyond that, not so much in terms of the heirarchy itself so much as the idea that peak experiences (including mystical experiences) are things which are easiest to achieve once certain psychological things are dealt with.

Assagioli is interesting reading. It is as if he throws Freud, Jung, and Dante into a pot, seasons with a touch of Hinduism and Arthurian legend and pulls out out a psychological theory which surprisingly makes sense.