Saw The Mousetrap at the HK Arts Theatre and really enjoyed it. Also live music, some good cover bands at Insomnia LKF with the best lychee martinis. See some of the orchestras in concert. City Chamber Orchestra Hong Kong and HK Sinfonetta perform some of the best concerts. Also the HK Chamber Music Society put on good concerts with or without an excellent dinner at the HK club.
HK hiking meet up or Microadventures for the active. You meet people/ expats of all walks of life. Seeing foreign films as opposed to your avg US Hollywood churn out. Take a picnic up to a scenic area on a hike and enjoy the view and food, plus a bottle of fizz / beer.
Not a big fan of junk trips. Prefer to kayak. Palm Beach on Lower Cheung Sha, South Lantau hires out kayaks, surf boards and other watersports . ( speaking of which, our former neighbour left his two man kayak behind when him and family moved and it's still there. Temptation kicking in.....lol)
Or live like the locals on weekends. Battle it out for a spot at The Metropole for dim sum or head on over to and IKEA outlet ( no passport needed despite the store becoming a country within a crowded city during weekends and lunchtimes.)
Personally, the Majesty Seafood Restaurant in central, opp Topshop has better food.
Most expats I know who have kids spend their weekends with other expats with kids. Even if they don't like the other expats. Expats with no kids, do other stuff with expats and locals with no kids.