As a clarification, CX does not have a First Class lounge at PEK or PVG. CX has a Business Class lounge in both places...I *suspect* this is your meaning. Note these are called the Cathay Pacific and Cathay Dragon (KA) lounges. KA is CX's wholly-owned subsidiary which flies most of the flights to PEK and PVG.

Welcome to the forum. If you have time search around, there's a lot of details about them around here. They're nothing to get too excited about F&B, although they're generally large and roomy and "good enough". But absolutely nothing to plan your day around. Just an afterthought if you have time in the airports.