Originally Posted by
corporate-wage-slave
You do get Flagship Access on 3 class domestics in the USA, provided it's transcontinental or has a leg outside North America.
Not all true. From AA.com:
First Class cabin on an American Airlines marketed and operated three-class nonstop transcontinental flight. Lounge access is also valid on a same-day itinerary that includes a qualifying transcontinental segment.
There are two-class transcon.
*Edit* And I quote the wrong one. CWS got it before me :-)