Laetitia Laurent, a South Florida interior designer, has long had her heart set on a Parisian pied-à-terre. This summer, with the dollar soaring and Parisian real-estate prices holding steady, she took the leap. The 42-year-old, who lives in Boca Raton, paid €758,000, or $758,606, for a 460-square-foot, one-bedroom in the Golden Triangle—the prime residential and commercial area between the Seine and the Champs-Élysées, in the French capital's pricey 8th arrondissement.