It's a Thursday afternoon. Your busy downtown office is driving you insane. The 3:00 appointment cancels, and suddenly you have a free hour. Hit the road, Jack! Ten minutes away is a picturesque, deserted, tropical beach where you can lie under a shady Australian pine tree and listen to the waves lap against the shore. Feel the stress disappear. Back in Jim Crow days, Virginia Key was a blacks-only beach and it remains a refuge, though of a different sort. Thanks to activists' tenacity, it recently was rescued from private development -- again. Windsurfers cherish the place because it's sheltered by offshore reefs. But the further south one walks, the more secluded and exotic it becomes.