The Transportation Hall boasts a 28m-long railway locomotive, a 1903 automobile and the sparkling ruby slippers from The Wizard Of Oz (1939).
But the highlight is Wegmans Wonderplace.
Like at KidZania Singapore, everything is child-sized, practical and hands-on.
Little ones can climb in and take the wheel of a tugboat, visit a "farm" and collect eggs from automated wooden chickens, shop in a market full of life-sized fruit and vegetables and then "cook" them in a mini-kitchen.
If your little tykes are getting cranky, calm them down and work up their appetites with just one more activity, a quick blow-offsteam run around the giant sculptures by Yoko Ono, Auguste Rodin and Henry Moore at the nearby Hirshhorn Museum and Sculpture Garden (hirshhorn.si.edu) before heading back to your base camp to get ready for dinner.
Eating with tots who have the attention span of gnats is always a challenge, even in the most childfriendly restaurants.
Fortunately, all the hotels mentioned here have the appropriate gear, hospitality and menus that go beyond cliched kids' fare of pizza and burgers.
At Four Seasons' Bourbon Steak, there is lobster (in a kid-friendly hotdog format) and a mini filet mignon.
At the Mandarin Oriental's Muze is a child-perfect view from the big windows: boats of all sizes on the river outside and helicopters (sometimes the green Marine One with the United States President in it) passing overhead.
Its best feature is a very large and fenced-in grassy area around its patio, where kids can run freely.
Kimpton Hotel Madera's (www.hotelmadera.com) Firefly restaurant trades the chicken-nugget trope for healthier and more interesting items such as apple wedges, buttered noodles with Parmesan, chicken soup, braised greens and shrimp.
The showstopper is the appearance of a server with an unbaked cookie for your child to decorate at the table - and to eat at dessert time.
Start Day 2 at the Mall with a walk to see the monuments and memorials, including the soaring 170m obelisk of the Washington Monument.
Small fry will love the way civilrights leader Martin Luther King Jr seems to be emerging from a giant mountain of rock in a 9m-high stone sculpture.
For adults, there is an Inscription Wall the length of a cricket field, which features quotes from King's speeches, sermons and writings.
Although there are eight major memorials, end your walk with the most iconic, the stately Lincoln Memorial.
It fits the bill not only because of Abraham Lincoln's significance in US history and the grandeur of the almost 159-tonne marble sculpture of a sitting Lincoln, but also because, as every exhausted parent will appreciate, there are restrooms at the base of the classic Greek temple-style building.
Little ones will marvel at Lincoln's huge hands and feet
. For one smiling mum, the highlight for her kids were the 58 steps up to the statue. "They're just really busy running up and down wearing themselves out," she says.
If you are not worn out, there is still time to peek into two more museums. (Since the Mall museums are free, you can visit in short bursts without guilt.)
The National Museum of the American Indian (www.nmai.si.edu) is stocked with bows, arrows and quivers galore for kids already smitten with archery.
At the imagiNations Activity Center, your little tribe can sit in a tepee and try basket-weaving and walking in snowshoes.
Elsewhere, in the Native Beats Music Room, kids get to bang away on Native American drums.
Refuel at the museum's cafeteria, where your little diners can try a variety of Native American dishes such as wild rice, corn bread and buffalo burgers.
The joy of the Mall is that without taking a bus, train or taxi, the visitor is a short walk to the next activity.
At the captivating National Air and Space Museum (airandspace.si.edu), you will encounter a lunar lander, the Apollo space capsule and monster-sized planes and spacecraft hanging from the ceiling.
Your little astronauts will get to make and fly paper planes, launch kites and look through a giant telescope.
If you need a breather, check out the museum's daily Story Time.
Relax while someone else reads to your kids about winged creatures and trips to Mars.
The children can snack on freeze-dried astronaut ice cream available in the gift shop.
On Day 3, tell your offspring a real baby giant panda named Bei Bei is waiting to see them at the National Zoo (nationalzoo.si.edu).
There, kids can watch Bei Bei eat ice pops, climb a tree and wrestle with his mum, Mei Xiang.
Touring dad Mark Schamel says that not even a staring contest between his two-year-old son and a resident gorilla beats the Bei Bei visit.
There is also a miniature but real farm with hogs, donkeys, alpacas, goats and chickens for petting and grooming.
There is more nature in the city at the nearby US Botanic Garden (www.usbg.gov).
There, you can see rare orchids and carnivorous plants and your scamps can follow secret paths through the foliage and play with trowels, shovels and watering cans in the Children's Garden.
If you and your little ones still have energy, end the day with one of the lesser-known, but very interesting attractions in Washington: the US Bureau of Engraving and Printing (www.moneyfactory.gov).
"The Money Factory" offers short tours to watch millions of US dollars being printed, cut and stacked as well as old bills being shredded.
The gift shop even sells small bags of that play-worthy shredded currency.
If you want to attempt a grown- up meal downtown before you leave, Jaleo (www.jaleo.com/dc), Chef Jose Andres' restaurant, welcomes tots.
There are plenty of highchairs and booster seats and the extensive tapas menu has so many small-plate options that there is bound to be something even fussy little foodies will try.
But if the adults are pining for a dinner sans small fry, both the Mandarin Oriental and Four Seasons have well-vetted babysitters on their roster.
With one more day in Washington, live like a local before you pack up and steel yourself for the return flight.
All of Washington's public libraries are hotbeds of kid activities.
There is toddler story time and a dance party called Pop of the Tots with music, dance, instruments and a shower of bubbles.
The downtown Martin Luther King Jr Memorial Library is near the National Portrait Gallery (npg.si.edu), with its rubber-floor courtyard for crawlers.
The Shaw branch of the library is close enough to take a stroll on U Street, Washington's historic African-American area, once called "Black Broadway".
Another hot tot ticket is the mini-hipster hangout BloomBars (www.bloombars.com), where children and their grown-ups can drop in for toddler and pre-school Bollywood dancing, Rasta drumming and Spanish-language puppet shows.
For your last evening, a wonderful wind-down is a watery Washington goodbye with one of the capital's relaxing boat experiences.
Meander down the Potomac River with views of the Mall monuments on one of the Capitol River Cruises (capitolrivercruises.com), or rent a paddleboat in the Tidal Basin (a short walk from the Mandarin Oriental).
For DIY-ers, head to Thompson Boat Center (www.thompsonboatcenter.com), a stone's throw from the Four Seasons.
Put your little ones in life jackets and rent a kayak, canoe or rowboat and spend your time peacefully floating on the river, en famille, in the surprisingly cool capital of the US.
•Judith Ritter is a Boston-born journalist based in Montreal who often travels with her two young grandchildren.