I've been on 10 Carnival cruises, with my 11th booked for January 2011. (One Disney). 9 out of 10 cruises I booked with a travel agent. For my 10th I ended booking directly with Carnival because I was pricing a couple different ships, itineraries, and rooms. I booked my 11th through Carnival too.
I have never been contacted by a PVP from Carnival. I go on Expedia all the time and different travel websites to check prices and I go to Carnival's website too.