Finally nailed it.
US sells a 90 day trial. Silver is $200, Gold $400.
Presuming silver is *S, and Gold is *G (otherwise $600 for plat).
This is worthwhile for someone needing a second suitcase more than once in 90 days (couple on one flight/one pax on two).
People flying more, and it can be a big money saver.
There also should be lounge access if buying Gold and flying int'l.
@Dan, would make a nice post for the main site IMHO.