It is too good to be true if you are an AmEx Platinum Card member. The advertising is quite simply false and misleading. Only certain AmEx Platinum cards count other are disqualified contrary to advertising and their own FAQs at
http://www.airspacelounge.com/faq.php quoting: FAQ "I have an American Express® Platinum Card; can I enter the lounge free of charge? a. Yes, American Express® Platinum and Centurion members are permitted in the lounge free of charge" This is a lie just try to enter AirSpace at BWI without the "correct" AmEx Platinum. I have had one for over 40 years and was told it was not the right AmEx Platinum.