 They arrive very early each morning, and instead of the common plastic lounges used by the rest of us, they manage to nab one of the rare white four-poster beds that face the ocean. These sisters are 18 and 19 years old. Their outdoor bed sports gauzy white curtains on all four sides to protect whoever lies upon it from the sun. But the sisters draw the curtains back, creating a stage and lie out, perfecting their tans, often adjusting their bikini bottoms to check their progress.