If you want to see London at its most spectacular, go in 2012. In June, the city will celebrate the Queen's Diamond Jubilee with all due pomp and circumstance (including a huge parade and a flotilla of 1,000 boats on the Thames). And in July and August, of course, the eyes of the world will be on London as it hosts the 2012 Olympic and Paralympic Games. Will it be crowded? Sure. But it'll be unforgettable.

Here's what we tell friends who are visiting New York for the first time: See the Empire State Building, Times Square and the museums first. Go to at least one Broadway show. But then pick a neighborhood—any neighborhood—to explore in-depth. It's impossible to see all NYC has to offer in a single trip, but focusing on, say, African-American culture in Harlem or immigrant history on the Lower East Side can be quite rewarding.

Rome is one of those cities you could spend a year in and still feel like you've barely scratched its surface. Amazing historical sites, mind-blowing art—and then there's the food. Stop at the Forno in the Campo de' Fiori for a fresh slice of pizza bianca (cut from a piping hot six-foot-long slab of it), buy some tiny strawberries in a street market, and make it your business to find the city's best gelato. Someone has to do it.

Everyone wants to see the major sights of Paris—and it's true, it'd be criminal to leave town without visiting the Louvre, the Eiffel Tower, Notre Dame, etc. But to truly appreciate this city, you need to get away from the tourist sights. Plunk yourself down at a table in a small café, enjoy a glass of wine and watch le monde go by.

Who cares about a little fog (okay, a lot of fog) when there’s so much to do in San Francisco? By day, explore Fisherman’s Wharf and the Aquarium of the Bay, ride a cable car, and stroll around the Presidio; by night, have a fabulous dinner (at a Michelin-starred restaurant or a tiny place in Chinatown), then hit some of the best clubs on the West Coast.

It's easy to lose yourself in the narrow, winding streets of the Medina—and we mean that both literally and metaphorically. Smell the spices in the air, brush up on your haggling at a local souk, then sip mint tea in the Majorelle Garden. End your day lounging in the rooftop garden of your riad, watching the sun set over this timeless city.

The city of Istanbul is a vibrant mix of many cultures, due in part to its location (straddling Europe and Asia across the Bosphorus Strait) and, well, in part to its history of getting conquered. The Hagia Sophia, for example, was a church, then a mosque and is now a museum. You'll spot Greek, Roman, Byzantine and Ottoman architecture around town.

Architecture buffs should make a beeline for Barcelona. The medieval and Roman buildings in the Gothic Quarter (Barri Gotic) provide quite a contrast to Antoni Gaudi's fanciful architecture, which you'll find all around the city. A visit to his still-unfinished Church of the Sacred Family (Templo Expiatorio de la Sagrada Familia) is a must.

Most travelers don't come to Siem Reap because they're dying to explore Siem Reap—they come to Siem Reap because it's the closest city to the amazing Angkor Archaeological Park. And Siem Reap is absolutely fine with that. In fact, it's a bit of a tourism boomtown. You'll find a wide range of hotels, restaurants and nightclubs here, many of them brand-new.

Berlin is a multi-faceted city. So feast your eyes on modern architecture, then visit a Baroque palace. Spend the day at one of the world's finest zoos, then spend the evening listening to one of the world's finest orchestras. Most travelers make a point of taking in more serious WWII-related sights as well. TripAdvisor travelers give particularly high marks to the grim but thorough and thought-provoking Topography of Terror exhibit.

If you’re a history buff and a die-hard foodie, Chicago’s your kind of town. Take an architectural-history walking tour, then dine at Alinea (the most celebrated molecular-gastronomy restaurant in the U.S.). And don’t miss the Museum of Science and Industry, the biggest science museum in the Western Hemisphere.

Everyone’s heard the Doors of Paradise, the Duomo, and Michelangelo’s David are captivating, but in Florence, beauty can sneak up on a traveler unexpectedly. You’ll duck into a random church to escape the heat only to spend two hours staring at an impossibly pure blue in a fresco. Or you’ll consider writing a sonnet about pear gelato. It’s just that kind of place. Don't miss the sunset over the Arno and the famous wines of the Chianti region just south of town.

We think it's time to stop calling Buenos Aires the "Paris of South America." As anyone who's been there will tell you, this city has a spirit all its own. Spend a day visiting the city's many fine museums and the amazing Recoleta cemetery, then hit the modern Puerto Madero neighborhood at night to take your pick of the city's coolest restaurants and clubs.

Sydney has so much to offer—amazing museums, a vibrant arts scene, great beaches nearby, restaurants serving any cuisine you can think of—that everyone who visits inevitably becomes jealous of the locals. If you visit during the Vivid Sydney festival (late May-early June), you'll be treated to spectacular lighting installations all around the city.

The Summer Palace, the Forbidden City, the Temple of Heaven—what traveler can resist attractions with such poetic names? You'll also find stunning contemporary architecture in Beijing, and no visit would be complete without seeing the Great Wall of China. (TripAdvisor travelers recommend the section at Mutianyu because it's less crowded.)

We hear the question, "What’s the next Prague?" a lot. But while we’re all for discovering great new destinations, we hardly think Prague is over. Sure, everyone’s heard of it, but it’s still a grand city with extraordinary historic and cultural sights, and it’s definitely worth a visit. The often-rebuilt Prague Castle has overlooked the city since the 9th century, and the synagogues and cemetery of the Jewish Quarter are must-sees. Nightlife here is diverse and plentiful, from trendy clubs to sophisticated wine bars to late-night cellar bars.

In Las Vegas, you’ll find restaurants run by the world’s finest chefs, opulent spas, and sophisticated hotels… along with penny slots, Elvis impersonators, and indoor Venetian canals (complete with gondoliers). Why come here? Because there is simply no other place on the planet like Las Vegas. And we wouldn’t have it any other way.

A lush gem presided over by two towering peaks, Bora Bora makes quite a first impression. Admire turquoise lagoons from the perimeter road that traces its 19-mile circumference. There is a bounty of activities packed into this small space. Get your feet wet at the Lagoonarium, the Diving Center, the Coral Gardens or the Leopard Rays Trench. After an energetic day, contemplate these watery wonders from the lofty heights of 2300-foot Mount Otemanu or while strolling through palm-studded Matira Point.

Shanghai is the cool, confident face of modern China, and its energy is infectious. Drink and dance the night away in fashionable clubs and bars, or watch the crowds go by in People’s Square. And if you haven’t eaten Chinese food in China, be prepared for your mind to be blown.

Honolulu is a legendary surfing destination. But even if you don’t know a boogie board from a surfboard, you’ll find a beach here that appeals to you (and, if you want to learn the difference, you can find a great instructor to teach you). Swimming, kayaking, snorkeling, outrigger canoeing or just sunbathing… it’s all available in Honolulu.

Hit the beach in Santa Monica or Venice, go celebrity-spotting at the Chateau Marmont, ride the roller coasters at Universal Studios Hollywood… there are almost too many options! History buffs will love a visit to Olvera Street, the city’s oldest and home to many stalls selling Mexican crafts. And for something you won’t see anywhere else, check out the bubbling (and, erm, uniquely fragrant) La Brea Tar Pits.

With a new mission statement, "Soul Is Waterproof," New Orleans is back. The city's walkable historic core, including Faubourg Marigny, the French Quarter, Warehouse and Arts District, Magazine Street, the Garden District, Audubon Park and Zoo and St. Charles Avenue, are flourishing anew and eager to welcome visitors once again. Whether for the jazz, the nightlife, the hopping gay scene, the food, the culture, or for that distinctive joie de vivre, it's time to head back to the Crescent City.

Cape Town glistens at the southern toe of the African continent. Tourist brochure-views at Blaauwberg Beach and Kirstenbosch National Botanical Gardens are within easy driving distance of "The Mother City." The Cape of Good Hope Nature Reserve provides sweeping sea vistas, hiking trails and wildlife encounters. On a more somber note, travelers can visit Robben Island, the prison where Nelson Mandela was held for 27 years.

Spend your time in Chiang Mai visiting historic sites, eating delicious street food, and, oh, perhaps bathing and feeding an elephant. Several local elephant camps compete for your business (read our reviews to determine which one is best for you). Chiang Mai is also a great place to take a cooking class, according to TripAdvisor travelers.

It's easy to love Dublin. Where else can you legitimately learn about local history and culture by visiting multiple pubs? (Side note: you can't say you hate Guinness until you've had it in Dublin. It's different. And it's fantastic.) Leave time for a stroll along the Liffey, a peek at the Book of Kells and, on a more serious note, a visit to the Kilmainham Gaol Historical Museum.