The best airport lounge in the world is probably the Air France La Premiere lounge at Paris Charles de Gaulle. It has true gourmet dining, a spa, and a car service to take you to and from the plane. However, almost nobody can use this. You actually need to be an Air France first class passenger. They only make one award seat available per flight, and you have to be a Flying Blue Platinum member to book it.
However there are many great lounges that most of us have real world access to. These are my favorites.