What about Marty Schottenheimer?
I always liked this guy and believed he had the ability to not only get the teams he coached into the playoffs but could win the SB. He's has the credentials and experience to make Miami a winner again and perhaps a SB contender. At 68 he should still have plenty of fight left in him to make the Dolphins a class act again. His abilities apparently have meant something to many assistant coaches who worked under him who today are HCs.