I view the Diaoyu/Senkakus as different from Paracels, since the US captured Diaoyu from Japan, so it wasn't out of the ordinary for the US to return it to Japan. Over the same period of time that Japan held Diaoyu, China was actively contesting control of Paracels, so it has a much stronger diplomatic case for the Paracels.
I can't speak to the Philippines and fishermen issue, as I am not well informed of the situation. I thought China engaged in exactly the same behavior, though, which would make the Philippines' action more understandable.
In any case, as I was writing in another thread, China should be more proactive in explaining to the American public its position on the issue. Right now, it's easy for Americans to understand the case for supporting Japan, or the Philippines, or whomever: they will offer us an alliance, and possibly bases. China will never offer the US an alliance--you and other Chinese users have made that clear. It's always easier to be friends with someone that wants to be your friend than someone who wants to be your rival.
That said, I admit that the US could approach the situation with a better diplomatic solution, or at least a more quiet diplomatic solution so as not to push China into a corner through public statements.