I've always enjoyed the salon, where we discuss literature while sipping fine sherry. (Dry before dinner, sweet after - or perhaps port.) The reference library between rows 2 and 3 can be handy for resolving tricky points. Fortunately, it's quite comprehensive.
There's often a bridge game going in the rear left corner.
The hot tub toward the front has its fans, though I seldom use it because my tuxedo water-spots easily.
A few people sometimes use the darkroom, but that's fallen off with digital cameras. They may use the space for a tanning bed before long, or relocate the masseur who regularly complains about being hit by the ends of pool cues.
A few people use the business center, but not many. That's just as well, because the dart board is nearby.
There's usually a line at the ATMs before landing, so you'll want to get your destination currency early.
Enjoy your flight!