The Amex Centurion lounge in Mia is great and right on the D concourse in the middle of the Aa gates. Two guests and then for $50 you can get an additional guest in. Puts the Admirals club to shame and if you want to have lunch they serve a real meal that is as good or better than anything you can buy in the terminal. Also, drinks are free and all the top shelve brands are included. Not going to be a way to sneak that fourth person in though.