I forget the lounge at SIN that's open 24 hrs, but that's a solid PP lounge. Got dinner and a good night sleep there. Before the Amex lounge opened at IAH the KLM lounge was solid enough, mainly due to free pour liquor and semi solid food. The No.1 Lounge at LHR is also pretty good.
Most PP lounges are pretty forgettable, but occasionally there is a gem in the rough.