North and South America

The Trip: This train hits the northwestern countryside, setting off from Vancouver in the evening (leaving a few hours of daylight in which to play I Spy across the prairie). After a good night's sleep, passengers can hop off in Jasper, Alberta, to explore the Rockies.

The Train: The refurbished 1950s Art Deco–style trains have adjacent two-bunk cars with removable walls that are ideal for families. In the Skyline Car, an activity coordinator entertains kids with games, movies, and art projects.

Caveats: The trains are clean and comfortable but lack glitz.

Details: From $1,940 for two adults and two children, for two one-way double bedrooms and meals.

The Trip: This weeklong ride moves south from Tucson, Arizona, through the desert and along Copper Canyon (which is even deeper than the Grand Canyon). The train stops in pretty villages—where kids can explore trails that lead to flocks of goats—before climbing over the Continental Divide.

The Train: Built in the 1940s, each roomy, nicely restored suite has two bunks, a bathroom, and romantic wide windows. Don't miss the glass-domed car or the open-air deck.

Caveats: While kids find this route engaging, it's also popular with retirees.

Details: $3,595 a person for a round-trip double compartment, five nights at hotels, and most meals.

The Trip: Named after the first American who came upon Machu Picchu, in 1911, the Hiram Bingham is a swanky way to travel between Cuzco and the famed Incan ruins. The three-and-a-half-hour ride follows the Inca Trail past farmland and rivers; kids can pass the time by counting waterfalls.

The Train: The 1920s-style cars are old-world luxe—with services to match. A five-star brunch is served in the morning, high tea is offered at Machu Picchu in the afternoon, and a live mariachi band entertains on the return ride.

Caveats: The train only operates on one timetable, preventing you from staying in Machu Picchu overnight.

Details: $550 a person for a round-trip seat, meals, and a tour.

Europe

The Trip: This 17 1/2-hour journey takes you as close as you can get to Santa's North Pole. Leaving Stockholm in the evening, the train follows deep fjords, passes the Arctic Circle at Murjek, and stops at a reindeer farm outside Kiruna, where families can spend the night in the nearby ice hotel.

The Train: Cars, including the three-bed sleepers, have a typically Scandinavian utilitarian look. They're equipped to entertain tots on board, offering DVD viewers.

Caveats: It can be tough to lull kids to sleep in the land of the midnight sun, and temperatures top out in the 60s.

Details: $300 for a one-way triple sleeper.

The Trip: While the first Orient-Express ran between Paris and Istanbul, the British Pullman, which runs day trips between London and either Chatsworth or Bath, is its only train to allow kids. Chatsworth is a baroque palace with 1,000 acres of wooded grounds (and a hedge maze); Bath's big draw is the ancient Roman spa.

The Train: Parents will love classic details like Edwardian-type marquetry and brass fittings, while kids will be fascinated by the Orient-Express legends—prep them with the Agatha Christie novel.

Caveats: The historic destinations get crowded with bus tourists.

Details: From $540 a person for a round-trip seat, tours, brunch, and dinner.

Asia

The Trip: India can be a daunting place to explore, but this train streamlines the experience. The weeklong journey goes from Delhi to the Taj Mahal. Along the way, kids can roar at big cats at Ranthambore National Park and trade their train seats for elephant and camel rides.

The Train: Each car has a different former state of India as its theme and is outfitted with warm wood, brilliant fabrics, and panoramic windows.

Caveats: It only runs between September and April, making the trip hard to coordinate with school vacations.

Details: From $2,000 a person for a round-trip triple-bed cabin, meals, and a Delhi tour.

Africa

The Trip: The wood-paneled Blue Train is like a five-star hotel on rails. It's also one of the best ways to see the mountains and plateaus between Cape Town and Pretoria (a 27-hour trip)—and you can even spend a few days at a game lodge for some safari time.

The Train: Lounge cars—with games, plush sofas, and libraries—connect the suites, which feature bathtubs and white linens. The local food (like Karoo lamb) and wine are spectacular.

Caveats: This train is best for ages 6 and up—i.e., kids who can behave on board and on safari.

Details: From $1,250 a person for a one-way deluxe suite and meals.

Australia

The Trip: This overnight journey cuts across the middle of Australia, from Adelaide to Alice Springs. The scenery ranges from salt lakes to vast, no-civilization-for-miles plains; in Alice Springs, kids can ride camels and check out Aboriginal rock art.

The Train: The bright red cars seem straight out of a storybook, and the suites are comfortable, if a little bland. There's a lounge with arcade games, and the dining car serves delicious grilled kangaroo and fish and chips.

Caveats: This train visits neither Sydney nor Melbourne.

Details: $836 an adult and $572 a child for a one-way Gold Kangaroo double sleeper and meals.