Kudos Miami! I just took this a couple of weeks ago on a long layover. Loved it! Here is my online review of the Miami Airport Flyer: http://www.thisishowyoudoit.com/miami-airport-to-miami-beach-south-beach/
Best Airport Transportation Miami 2012 - The Airport Flyer (Route 150)
Ever visit a city where the public transportation actually works? Like Minneapolis, where people take the light rail from the airport? It feels like you've escaped from the hinterlands into the Capital. (Yes, that's a Hunger Games reference.) Miami will probably never have good public transportation, what with our perpetually inept and greasy-palmed collective of politicians. But depending upon your starting point, getting to Miami International Airport by bus is — believe it or not — pretty damn painless. The Airport Flyer, as the express route is called, travels from South Beach to the airport and back with only two stops: one in Mid-Beach and one at the Earlington Heights Metrorail Station. It costs $2.35, a far cheaper option than cabbing it or parking long-term. If you don't live on the Beach, your journey gets more complicated once you transfer at Earlington Heights — but hey, what do you think this is, Seattle?