The gist

Perhaps a little less famous than the canyons and chasms of Arizona and Utah, Wyoming is, nonetheless, a remarkable slice of the American West – home to the miracle of geography that is Yellowstone National Park. With its spurting geysers and roaring waterfalls, this is scenery spectacular and noisy enough to capture the imaginations of even the youngest travellers, while being readily accessible from Denver – the modern capital of Colorado – whose museums and eateries will frame the start of your trip.

Further information: colorado.com; denver.org; wyomingtourism.org; visitidaho.org, our-rv-lifestyle.com/things-to-do-in-colorado

Days 1-3

Pitched on the edge of the Rocky Mountains – to the point that it is known as the Mile High City (it sits at an altitude of 5,280ft) – DENVER is also a playground for youngsters. The Children’s Museum of Denver (mychildsmuseum.org; general entry £6.50) is split into a range of interactive areas – The Assembly Plant, where kids can construct helicopters and buildings; Bubbles – described as ‘a world of soapy science’; Fire Station No1 – which makes use of a real decommissioned fire engine as an exhibit. Denver Art Museum (denverartmuseum.org; adults £8) – one of America’s finest galleries, with works by the likes of Picasso and Matisse – makes a real effort to engage with children. Admission is free for under-18s, there is a Just For Fun Center, where the very young can play, and there are art-making facilities for those keen to paint and draw.

The Museum of Nature and Science (dmns.org; adults from £9.50, children, three to 18, from £6.60), meanwhile, boasts an IMAX Theatre, a sky-gazing planetarium and a host of huge dinosaur skeletons – whose stories are brought to life by clever multimedia displays.

STAY: The Four Seasons(fourseasons.com/denver) looks after children with its rooftop pool, games consoles and child bathrobes. Family rooms cost from £274.

Day 4

Take Interstate 25 due north of Denver, cross the state line, and halt in Cheyenne.   The Wyoming capital is a pleasing pit-stop. You can find flavours of the frontier era at the Old West Museum (oldwestmuseum.org adults £6.50, under-12s free), with its 150-strong cluster of horse-drawn wagons, 1850s clothing and interactive children’s gallery.

STAY: The Little America Hotel (cheyenne.littleamerica.com) sits in 80 acres of grounds – offering a heated outdoor pool and family-sized rooms for £77.

Distance in the day: 101 miles.

Day 5

Forge north-west along Interstate 80 to the tiny town of Rawlins. This is a day of wild scenery, as the road flits past the north edge of Medicine Bow-Routt National Forest (fs.usda.gov/mbr), a million acres where Native Americans once crafted mahogany bows.

STAY: The Best Western Cottontree Inn (bestwesternwyoming.com) in Rawlins has an indoor pool, and offers family-sized rooms for £98, with breakfast.

Distance in the day: 149 miles.

Day 6

Take the 287 north-west from Rawlins. This is a long day’s travel, but it’s made worthwhile by Grand Teton National Park (seven-day permit £19 per car; nps.gov/grte). The American West at its most visually dramatic, the 40-mile long Teton range wears a cap of snow even in summer.

STAY: Dornan’s Spur Ranch Cabins(dornans.com/cabins) within the park has two-bedroom cabins with full kitchens from £183. Distance in the day:256 miles.

Day 7

Enjoy this epic setting. Families can hike along the likes of the Lupine Meadows Trailhead – which is as idyllic as it sounds. Wildlife is plentiful here and it’s not uncommon for walkers to spot deer, elk or moose. Alternatively, no trip to the West is complete without a horseback ride, and excursions are on offer via Grand Teton Lodge Company (gtlc.com). Gentle one-hour rides, suitable for children, cost £29 a head. Longer two-hour trips in the saddle cost £48.

Days 8-10

One of the joys of Wyoming is that you can swap Grand Teton National Park for Yellowstone National Park (nps.gov/yell; seven-day permit £19 per car) in under an hour, heading north on the John D Rockefeller Jr Memorial Parkway, which links these two protected wonderlands. Yellowstone is a true American must-see – sure to entrance junior minds with the raw power of its landscape. Its most celebrated resident, the geyser Old Faithful, bursts into life every 63 minutes with a screaming outpouring of steam. And while the Grand Canyon of Yellowstone cannot quite match its namesake in Arizona for size (it is ‘ just’ 24 miles long), there are ‘oohs’ and ‘aahs’ to be uttered where the Yellowstone River dives into it in two stages, as Upper and Lower Yellowstone Falls.

STAY: Old Faithful Inn (yellowstonenationalparklodges.com) has been in business since 1904 – next to the star attraction. Family-sized rooms cost from £145.

Distance in the day: 27 miles

Day 11

It is easy to end the trip by visiting a third US state. Leave Yellowstone by going north-west on the 287, cross into Idaho, then take the 20 south-west to Idaho Falls. From here, you can take a flight back to Denver – but before then, cool your heels in a pretty city where the Snake River veers over a small drop to create the water feature in question.

STAY: The Hilton Garden Inn (hiltongardeninn3.hilton.com) Idaho Falls makes for a soft journey’s end, with its kids’ menu and comfortable family rooms for £94. Distance in the day: 140 miles.

Your Hertz Hire

11-day car hire with Hertz starts from £628. Pick up at Denver International Airport and drop off at Idaho Falls Regional Airport. hertz.co.uk