Miami Beach via public bus from MIA

Here'e what I do when laying over in Miami -

You can catch the Miami-Dade 'J' bus line from the airport - lower level ground transportation - and ride it direct to Miami Beach. Takes about 50 minutes. Ride it all the way to the beach - you want to get off when the bus makes a left onto the last street (forget its name) before the beach. You're then a block from the beach and the boardwalk. You can rent a lounge chair and sleep the day away; you can visit many of the beachfront bars or pick up a discrete paper bag and mix your own. Pack your swimwear in your carryon - Nothing like a swim in the Atlantic between flights!