Less than a decade ago, Miami's inner city was mangy. The tropical city could have become the next Detroit. When businesses, law firms, and government offices downtown closed, few people remained in its seedy core, fleeing to suburban Miami-Dade and Broward counties for their gated, manicured subdivisions and soccer fields, or to the glamorous nightlife across the causeway in sleek South Beach. But that's all changed. Miami is booming again. Construction cranes dot the skyline as a new wave of baby boomers, international residents, and businesses converge on the city. Call it the tale of two cities: Detroit sought to...