that's pretty interesting TW - my experience has always been the reverse. I use the travel sites as a guide, find what I want and then go directly to CO's site and book directly. Always saved $$, never higher.
Most of the travel news (correct me if I'm wrong Barb) coming out these days seems to indicate that the airlines are pricing their own sites the lowest and won't give anything away. Many hotels too.
As I said, I always use the travel sites for guidance and then check myself directly.