I was 19 when I went into the Koru Lounge (Air New Zealand) at SYD and AKL. The best thing about it was the free food (pretty decent) and free alcohol. Since I was over 18, I was allowed to drink (Legal age in Australia and New Zealand is 18). I should have used my water bottle I brought and fill it with some white wine. :P
Mostly it's just for a 19 year old college student to goof around in and be like... ohhhhh, ahhh... that's shiny. Ohhhh... shower *jumps in shower*
As for Red Carpet Club (United Airlines), it's just quiet... when there aren't many kids around. Really it doesn't matter if the lounge had wi-fi, SFO offers free wifi... but probably slower with all the people on there.
I'm flying on Economy... I'm sure gonna miss the Koru lounge.