Across the country, stylish hotel properties are becoming home to a new breed of retailer, swapping 50-cent postcards for $5,000 jewelsSig Ward, a Manhattan Beach, Calif.–based jewelry designer, scored a coup at a recent trunk show in Hawaii. She sold $34,000 worth of earrings, opal and diamond chains, and a bangle to a local resident, who dropped by on her way to the gym. (She never made it.) “She wasn’t coming to see me or the jewelry,” says Ward, who also sold $27,000 of jewelry to a Japanese customer that week. “You just never know—and the shopper never knows.” The most surprising aspect of those sales? The less-than-traditional location: Makamae at Four Seasons Resort Lanai at Manele Bay in Hawaii. The boutique was designed and is curated by Seaside Luxe, a Los Angeles company specializing in high-end resort retail. “We’re not your airport ­souvenir shop,