A Paris storefront.   (Photo: Barry Lewis/Corbis)

London
When to go:
January 16–21, to take advantage of MLK Day.

Flight to take:
Virgin Atlantic’s economy seats (from $236 one-way; virgin-atlantic.com).

Hotel to book:
In the rapidly gentrifying East End, the Hoxton Urban Lodge is famous for its £1 room sale (but you need to be on the mailing list and act quickly; hoxtonhotels.com). Even its regular rates (from $75 to $255) are a great deal.

Where to eat:
Gordon Ramsay’s latest endeavor, York & Albany (gordonramsay.com), is a combo deli-restaurant-hotel in Camden. The prix fixe lunch is $20.

What to do:
The Annie Leibovitz exhibit at the (free!) National Portrait Gallery runs through January (npg.org.uk); the new Egyptian gallery opens at the (also free!) British Museum then, too (britishmuseum.org). Edgier galleries, like the White Cube (whitecube.com), are clustered around Hoxton Square.

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Rome
Week to go:
January 2–9, to catch the tail end of the Natale All’Auditorium, Rome’s homage to Christmas.

Flight to take:
Euroflyusa.com has round-trip fares for $559. Travel is valid on Fridays and Sundays through March 27.

Hotel to book:
Casa Howard (from $205; casahoward.com) has two locations near the Spanish Steps and a pay-in-U.S.-dollars offer that gets you 40 percent off a five-night stay (not available Dec. 15–Jan. 5).

Where to eat:
Fish is the draw at Acquolina (acquolinahostaria.com), the latest from Angelo Troiani, who earned a Michelin star at Il Convivio.

What to do:
Rome is known for ancient architecture, but the Auditorium Parco della Musica (auditorium.com), the very modern Renzo Piano–designed performing-arts center—encompassing three concert halls, restaurants, bars, and an outdoor theater—is a contemporary classic.

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Paris
When to go:
January 26–29. The weather is iffy but there are fewer tourists, and every store is in the midst of a massive winter sale.

Flight to take:
Open Skies has premium-economy seats (52 inches of leg room and a 140-degree recline) for $599 each way (flyopenskies.com).

Hotel to book:
The seventeen-room Hotel du Petit Moulin (from $248; hotelpetitmoulinparis.com) is a fantastic, and fantastical, hotel by Christian Lacroix. Not hostel-cheap, but its Marais location makes it equidistant from grungy-cool Bastille and boho-chic St. Germain.

Where to eat:
Le Gaigne, a twenty-seater helmed by talented young chef Mickael Gaignon ($24 prix fixe lunch; restaurantlegaigne.fr).

What to do:
Sales only happen twice a year in France, and they’re massive; as much as 80 percent off at department stores like Galeries Lafayette and Printemps. Near the hotel, boutiques like Vanessa Bruno, A.P.C., and Erotokritos line the rue Vieille du Temple. Get the tax-free V.A.T. forms at every store and mail them from the airport; it’s a minor inconvenience that refunds generously.