When asked about the difference between cedar and pressure treated [pt] one of the contractors said, "pt is fine for decks, 'cause they're built tight and supported/fastened to the ground so many places, that the normal warping/etc that happens isn't visable. When you use pt for a fence, it'll bow all over the place"
I built a deck out of pt at my previous house, and sprayed it almost every year (took all of an hour or so). Besides a few pieces that were bad to start out with, it looked pretty much the same after 8-years.
We plan on staying at this house for at least the next 10-years, and part of the purpose is to keep my 2 sons in the yard. At it's closest, the fence is about 120 feet from the home, so we're aiming for privacy/sound. I guess I'm just looking for someone else to validate the need for all the extra cost of cedar.