When I was with Ministry in Human Sexuality, I took a couple of classes at the University of Nebraska - Lincoln in personality theory. I appreciated very much the thought of Maslow and Ken Wilber: in other words, developmental psychology. Wilber's synthesis of many developmental theories in both Eastern and Western psychologies made a lot of sense to me. I would highly recommend Transformations of Consciousness; Conventional and Contemplative Perspectives on Development, by Ken Wilber, Jack Engler, and Daniel P. Brown.
From a very different point of view, perhaps, I found the theory of
George
Kelly, a psychologist who was first trained in physics, very
interesting. (See Kelly, A Theory of
Personality; the Psychology of
Personal Constructs.) His thought emphasizes the freedom of the
individual in "construing" one's own reality. One of his points, that
we think by comparing and contrasting one thing with another, seemed to
make sense as well. If this interests you, visit this link for
more.
In my case, I think a lot in continuua, but I haven't figured out how continuua fit in with PCP (if you have, send me a link!). For example, sexual orientation is not a two-dimensional either-or: either gay or not gay, heterosexual or homosexual. Sexual orientation is multivariant and each variable has a continuum of gradations. See Klein, Two Lives to Lead: Bisexuality in Men and Women.
In addition, I have
also found these books to be of great interest and value: