Been to the generic airport lounge (AY, BA...) and it was nothing to write home about. The CX lounge was also mediocre, there's a sort-of good view (for PEK) but it's not likely to be anything exciting at that time.

If you have time (and access) you could try all of them, but the honest tip would be avoid spending time at PEK :P Either lengthen the layover to go into the city instead or shorten it so it's less painful.