Priority PAss (in my experience) has been a great investment as it allows you access to a pretty good range of lounges aroud the world. I find it particularly useful in asia and europe where a lot of times the have a lounge in the landside area (where most airlines dont have their lounges) or else in an area more convenient to your departure gate.

Plus if you dont fly business or first these are sometimes the only decent places to sit for a while.

Also, they have now added USairways Clubs to the list so many more options in the US.

So in short it is a pretty good deal. But make sure you go with the @ $200 unlimited access membership.