ladies' lounge vs watering hole

ladies' lounge

noun
  • A room in a pub or hotel, separate from the main drinking area, in which drinks are served; originally a place for women to drink in when not welcome or not comfortable in the traditionally male-oriented public bar, and latterly a more genteel area than the public bar. 

  • Used other than figuratively or idiomatically: see lady, lounge. 

watering hole

noun
  • A bar or other local drinking establishment. 

  • A depression in which water collects and where animals come to drink. 

How often have the words ladies' lounge and watering hole occurred in a corpus of books? (source: Google Ngram Viewer )