I see no reason why Miami/Dade would be off limits to those retirees who like big-city advantages and who know some Spanish, do not feel threatened by the prevalence of that language. Much of the crime and disadvantages there are tied to specific areas and neighborhoods easily avoided with a little savvy.
But you will note that I state that the best retirement area generally for anglo-americans is the coast region of just three counties: St Johns, Duval, and Nassau.
Those who are going to live behind total Air Conditioning can pick the gulf coast or central areas, but us old liners hate to turn on the AC, and up here we don't really HAVE to, not usually, er...not too often, anyway?