Millionaire's Row is nice but totally "dead" ... stick to South Beach if you don't want to feel like an 80 year old retiree!

15th street between Drexel & Pennsylvania is cool because it's off Washington (less noisy) but TOTALLY close to everything, including Lincoln Road. It's right around the corner from EspaƱola Way, the quaint Spanish-style street with a plaza.

Are you looking at a rental there? The only thing I would recommend is that you try to get a second floor unit. Some buildings there have units with the door just about next to the sidewalk. Not that you'll be totally unsafe or anything, but a second floor unit would be better.