Jenni Dahling, LAJ, and the two Kristen's (Top Bucks and X-Biz), are all people whom I respect as Marketing people. There are many others, but those individuals come to mind immediately because of their breadth of knowledge, and their willingness to mentor and help others learn, plus they are all consummate networkers.
I should add Brad Mitchell to that list, since he can work a room like few others I've seen, and is one of the most well-respected people whom I know in the adult industry.
ADG