I think China made some serious mistakes when it antagonize almost all of the country in it's periphery with regards to SCS. China should have been more diplomatic. Perhaps the US will find it harder to maneuver if China is more sophisticated in diplomacy with said countries as China is already the biggest of one of the biggest trading partner to those countries.
The US was mostly responsible for stirring up the SCS. There were problems between China and some of the other countries, but the negotiations were small and quiet. Then the US chose to magnify the minor disputes into major confrontations, and we see the results today.
I doubt there was anything China could do other than building up its defensive power. As @manqiangrexue said, if China made any concessions, the US would decide to push for more and more. The US would continue to press its advantage until China gave up totally. A capitulation by the Middle Kingdom would not be wise in an area as nearby and strategic as the SCS.