For those looking for a contemplative escape, Alison Bing, who has written 40 books for Lonely Planet, suggests Venice in winter, where the only traffic you’ll hear is footsteps. ”You cannot find a more serene place,” she said. Winter coats and boots are a must though, especially if you’re there on acqua alta (high water) days, when tides and winds cause the Venetian Lagoon to rise, leaving everyone ankle-deep in water. “Venetians love going out to bars when it’s high water,” said Ms. Bing, who has made the trip on her own and adored it. “Everybody takes the opportunity for an early happy hour.”

But isn’t Venice, to which this reporter has been in both summer and winter, a bit romantic for a solo trip? Ms. Bing dismissed the thought. “It’s kind of an exquisite melancholy,” she said. Her advice: go out to lunch and take along some local literature or a copy of Italo Calvino’s “Invisible Cities,” about an imaginary conversation between Marco Polo and Kublai Khan. “A couple of years ago I was reading ‘Invisible Cities’ alone, and oh, my God, if I had wanted to pick somebody up,” she said, “I couldn’t get people to stop interrupting me.”

For a cosmopolitan stew of eastern and western culture, Ms. Bing recommends Istanbul. Explore the Blue Mosque, the Grand Bazaar and the city’s many elegant nightclubs (including one called SuAda that has its own island), then indulge in an ideal solo activity: being scrubbed at a Turkish bath (if you’re accustomed to the gentle exfoliation offered by American spas, gird yourself).

One of the most frequently recommended cities for solo travelers is Dublin. While small, it still has a lot to see, be it the National Gallery, Dublin Castle or, as Ms. Banas suggests, the inside of a pub. “It’s just such a warm type of people,” she said. “You go inside, there are fireplaces roaring. There’s something very homey. And it puts you at ease right away.” (She recommends staying at a bed-and-breakfast instead of a hotel because it’s conducive to meeting other travelers, particularly during breakfast when guests gather and plot their itineraries.)

Amsterdam is another top choice. Sure, there are must-sees like the Van Gogh Museum’s temporary stay at the Hermitage Amsterdam, the Anne Frank house and Rijksmuseum (which is undergoing renovations until 2013 but is giving visitors the opportunity to view highlights from the Golden Age by Rembrandt, Hals and Vermeer all in one place as part of an exhibition called “The Masterpieces”). And there are new attractions like the Eye Film Institute and the Museum of the Amsterdam Canals. But visitors can also enjoy a beer at any number of lively bars (editors at TripAdvisor like In de Wildeman, which serves hundreds of varieties) or dance into the wee hours in clubs in Rembrantplein and Leidseplein. For a quieter evening, see a film at the Art Deco Tuschinski Theater, where patrons once went to hear Marlene Dietrich and Edith Piaf perform. An advantage of going when it’s cold? You might get the rare opportunity to ice skate on the frozen canals (in fact, the Canal Ring will be enjoying its 400th anniversary in 2013).

In London, you can stay warm wandering the usual tourist spots (Westminster Abbey, the National Gallery, Harrods), or bundle up for seasonal treats like Winter Wonderland in Hyde Park, where you can sip a cup of mulled wine and mingle around one of the biggest ice rinks in Britain.