In the race for top-tier office tenants, investors in South Florida's plushest office towers are considering their multimillion-dollar acquisitions only a first step in an aggressive business strategy.

In a market where most of the Class A properties date back at least a decade, bullish investors are spending millions to turn trophy buildings into best-in-class inventory for Fortune 500 firms, hedge fund managers, large law firms, corporate headquarters and other clients who want plush office suites to woo deep-pocketed clients.

“You can't change the concrete, but you can enhance all the finishes,” said Steelbridge Capital managing principal Jay Caplin.