If you do a Search on PriorityPass (probably in TravelBuzz) you'll find a lot of info. I've been a member for 2 years and am ready to sign up again. I like it because you're not tied to one airline's clubs- gives you more flexibility in your travels and you won't get screwed if your "loyalty" ailrine starts closing down lounges to cut costs.
We've been very happy with the selection but note that, last I checked, PriorityPass lounges didn't have any places available in CVG, SLC or CLT- could be a bad deal if you connect in any of these places or live there. Great international selection. W've used them in LHR, EDI, PRA, BUD, ZUR and probably more cities that I've forgotten at the moment.