As a Titanium I've always been offered breakfast in either the lounge or the main lobby restaurant. I assume Platinum's will be offered the same. We always went to the main restaurant as the selection is much better. This is one area where Tang Plaza is better than the JW... which only allow elite members to breakfast in the lounge (which I've always found to be good enough anyway).

Edited: to add that there are reports in the JW thread that restaurant breakfast is now being offered there as well.