I'm a regular user, but it comes free with my Amex card. I have used it at a few RCC's like PDX and I used it a few times at the US Air (former HP) clubs at LAX and LAS. For a few months US stopped accepting the card, but now it works again. Mostly I use it outside of the US.

Each month I get an email listing the changes. There are always a few new ones and some changes to the opening hours of certain clubs. But rarely do I see one go away, and if I do it is in some place like Libya.

Sorry, but the full lounge listing is for members only. I'm sure you can find out what you need to know here on Flyertalk though.