Expansions costing a combined $1.2 billion at the Eden Roc and Fontainebleau hotels have yielded the desired results. Nike will hold its European sales conference in Miami Beach at the Fontainebleu, a location it rejected earlier, because, as Ita Moriarty, the Greater Miami tourism bureau’s head of convention sales, conceded, it was a tired property. The Eden Roc spent $200 million gutting its original 1956 building and constructing a new 21-story hotel tower. Next door, the Fontainebleau is scrambling to finish a $500 million rehab of its main buildings, along with spending another $500 million on two condo-hotel towers with 658 new rooms. Both construction projects will end within weeks of each other — the Eden Roc’s main building reopened Friday, and the Fontainebleau plans a lavish return November 14 on the eve of a televised Victoria’s Secret fashion show. The Eden Roc’s new tower is expected to open a month later.