10. MEXICO CITY
Why The high elevation of this buzzing megalopolis keeps days crisp and cool—making it a welcome retreat during summer. The Condesa district is Mexico City's answer to SoHo, alive with outdoor cafés and a vibrant nightlife; the newest addition is the intimate, oval-shaped Superficial (102 Avda. Veracruz; 52-55/5241-2600), where the techno beats continue until the wee hours.
How to Get There Mexico Citybound planes take off daily. AeroMéxico, American Airlines, and Delta all offer direct flights from New York (five hours), Miami (3½ hours), Chicago (four hours), and L.A. (3½ hours).
Where to Stay With its rooftop bar, nueva cocina restaurant, and design by India Mahdavi, it's no wonder the hotel Condesa DF (102 Avda. Veracruz; 52-55/5241-2600; www.condesadf.com; doubles from $165) is red-hot.
Where to Eat Contramar (200 Durango, Colonia Roma; 52-55/5514-9217; lunch for two $54) serves the city's freshest soft-crab tacos and tuna-sashimi tostadas. For a star-studded repast, head to the nearby Polanco district's Hacienda de los Morales (525 Vàzquez de Mella, Colonia Morales, Chapultepec; 52-55/5096-3054; dinner for two $100).
Insider Tip Don't miss Cuban music on Tuesdays and Wednesdays at Casa Lamm (99 Álvaro Obregón; 52-55/110-899), a cultural institution in a 1913 mansion.
11. RIO DE JANEIRO
Why Brazil's most famous city is at once a big and bustling metropolis (population 6 million) and a romantic waterfront paradise, with 25 powdery beaches. Although it's technically winter in July, Rio's highs hover in the seventies.
How to Get There Overnight flights out of Miami and Atlanta mean you can start the day on the beach. And with just a one-hour jump on Eastern time, jet lag isn't an issue.
Where to Stay The Copacabana Palace (1702 Avda. Atlântica; 800/223-6800 or 55-21/2548-7070; www.copacabanapalace.com.br; doubles from $380) is an 83-year-old French landmark with winding staircases and the city's most glamorous pool scene. Coming soon: a $2.2 million spa. Hang out with the supermodel crowd at the beachfront Marina All Suites (696 Avda. Delfim Moreira; 866/376-7831 or 55-21/2172-1100; www.marinaallsuites.com.br; doubles from $318).
Where to Eat Ipanema's white-hot Forneria (112 Rua Anabal de Mendonsa; 55-21/2540-8045; dinner for two $50) is a must for fans of design, rock and roll (the jukebox counts more than 1,000 classics), and temptations like asparagus-Brie panini. Whether thirsting for Brazilian espumante (sparkling wine) or Krug, the cognoscenti of Carioca—as locals are known—head to champagnheria Ovelha Negra (120 Rua Bambina; 55-21/2226-1064).
Insider Tip Scheduled to open over the course of the summer, the Devassa complex (52 Rua Farme de Amoedo), just steps from the beach, is sure to draw the beautiful people with a brewery and a club that will showcase the world's top DJ's.
12. BUENOS AIRES
Why Onetime home to legendary tango crooner Carlos Gardel, Buenos Aires's Abasto neighborhood is—like the music—experiencing a revival. Immerse yourself in the history of tango culture at Gardel's former residence, Museo Casa Carlos Gardel (735 Jean Jaures; 54-11/4964-2015).
How to Get There Nonstop overnight flights to Buenos Aires run from New York, Miami, and Houston, arriving at about the same time that everyone is heading out for coffee and medialuna pastries after a night of tango dancing.
Where to Stay The Abasto Plaza Hotel (3190 Avda. Corrientes; 54-11/6311-4466; www.abastoplaza.com; doubles from $150) draws on the Belle Époque theme of tango's heyday, with Art Nouveau furniture and antique Victrolas. At the gift shop, buy a pair of Madreselva's sexy tango shoes, then join the hotel's free nightly dance class.
Where to Eat Dine on entrecôte and sip Malbec while dancers perform moves such as boleos and gaunchos at Esquina Carlos Gardel (3200 Carlos Gardel; 54-11/4867-6363; dinner for two $140), the city's top dinner club—and one of Gardel's old haunts.
Insider Tip Perfect your own moves with renowned tanguero Carlos Copello at his newly opened International School of Dance and Art (575 Anchorena; 54-11/4864-6229; classes from $3). You won't be an expert overnight, but you will be able to hold your own at any milonga in town.