One of my favorite benefits of an American Express Platinum card is the complimentary Priority Pass membership. I originally got it years ago where it lazed in my wallet without any use. This was until I started paying attention to domestic terminals that did not service my airline, and international terminals where the upper class lounges were overrun or inconvenient to the gate. Couple that with the fact you can't even access most domestic lounges, even with top tier status and a first class seat, and in the last few years my Priority Pass has gotten ample usage.
It's simple and easy to get in, if you have the American Express Platinum card. You can apply HERE
What's more it gives you access to the lounges no matter the class of service you are flying in.
A few of my favorite lounges where I use Priority Pass:
Cancun, International: Completely congested at most times, this lounge provides a quiet oasis, and if nothing else, somewhere to comfortably sit down and grab wi-fi.
LHR Terminal 3, No. 1 Lounge: Located on the floor above the British Airways lounges, you may ask yourself why bother with the extra flight of stairs, if you can get in the BA lounges. For one, at times it can be less crowded and the food is excellent. Fresh salads and food presentations are brought out regularly. However, they also have the Dermologica Spa, with a full array of spa treatments, for a price. Aspire has also opened in T3, but I have yet to make a visit.
LHR Terminal 2:Plaza Premium: This is great if you are flying BA or AA and transiting to an intra-Europe flight without first class. And you guessed, it they also have a spa, which is prefect to unwind between flights when you don't have airline lounge access.
See a pattern here? Yes, I like to burn my long layovers with a foot and leg rub to keep my circulation going in between long flights, or grab a facial to soothe my skin after the dehydrating flights, that champagne certainly does not cure. In fact, I usually double dip on the BA complimentary 15-minute Elemis spa treatments with any business or first-class ticket, then enjoy a full spa treatment at one of the Priority Pass spas.
With AMEX you also get the Centurion lounges which at this point are only domestic and some are certainly better than others. I have visited all, but the Houston location, and Dallas (DFW) is the stand out, though I feel all suffer from overcrowding.