I have heard many stories of domestic US first class passengers being denied access to the business lounges especially when flying with American Airlines. Is this official policy for most US airlines?
In other parts of the world, to deny access to a 1st class passenger is unheard of. Is this yet another example of the poor service offered by US airlines?

Can anyone confirm the policy for access by 1st class domestic passengers to the Northwest lounges?
As part of a world trip, I am flying NW from Vancouver to Minneapolis and I wondered if I will also be denied access to the lounge.