'First time in Vegas ma’am?” the taxi driver deduced from my dazed expression.

Despite having seen this neon wonderland in countless movies and television shows, I still wasn’t quite prepared for ‘the strip’ in the flesh.

Little did I know, however, that over the next week I’d see sights more surreal and incredible than anything Vegas could throw at me – and all of them completely natural.

My Grand American Adventure would begin and end in Sin City, but before that, I’d be hiking my way through two other national parks and traversing one of the most wild and dangerous valleys in the world – well, if you believe the John Wayne version.

After meeting the rest of the tour group – 12 intrepid travellers aged from 28 to 80-something – we boarded our bus and set off for Zion National Park.

One of the park’s most famous peaks is Angel’s Landing, and the climb to the top – 1,500ft above the valley floor, is also one of its most popular.

Following the advice of our guide Jeff, we were on the trail by 8.30am to avoid walking in the searing midday sun, but even that couldn’t help me on the last leg of the journey. One look at the people in front scrambling up and down an almost vertical cliff face, I wimped out, opting instead to walk the West Rim route to the perfect picnic spot.

There are walks for all abilities, with the easiest also proving among the prettiest. The 5km Pa’rus Trail traces the Virgin River and seems to capture the tranquillity and integrity of the park perfectly.

The next morning we left Zion, climbing the Colorado Plateau in our coach to Bryce Canyon National Park – and one of the most remarkable landscapes on earth.

Bryce is famed for its hoodoos – surreal rock spires in a kaleidoscope of colours that create forests made of stone.

Its elevation means that for around 200 days a year, ice and snow cover the park, melting during the day and refreezing at night, eroding the rocks from the inside and creating the hoodoos.

The walk around the rim gave plenty of photo opportunities, but getting in among the spires is the best way to appreciate the true scale, and fragility, of this bizarre landscape.

There are mountain lions and black bears at Bryce, although your chances of seeing them are slim.

Rockfall is another threat. The walk up the winding switchbacks of Wall Street, one of Bryce Canyon’s most spectacular hikes, is a must for any fairly fit visitor. But don’t linger too long, crumbling cliffs are common and the route is regularly closed off.

As well as its hoodoos, Bryce is famed for its dark night sky. So one night we convinced Jeff to drive us back into the park to see nature’s great light show. Experts say that even without a telescope you can see up to 7,500 stars here.

Back on the road, we made a brief stop to admire Lake Powell and Glen Canyon, before arriving at Monument Valley, Arizona, home to the Navajo people and the location of countless movies.

As our guide Leonard ran through the long list of movies shot here, I suddenly realised the Indians weren’t really the ‘baddies’ at all.

“John Wayne films are like horror movies for us because we always lose,” he chuckled.

We were also introduced to ancient petroglyphs (rock carvings), beautiful natural arches and traditional cedar flute music.

I suspect most of the men in our group would have liked to stay a little longer, saddle up, and live out their boyhood daydreams, but it was time to get our first glimpse of the Grand Canyon.

At 277 miles long, 18 miles wide and over a mile deep, it is impossible to comprehend the true scale of this wonder of the world.

I stood mesmerised as the changing light brought the canyon to life. With every passing cloud it seemed to shift, its layers deepening to bold reds and greens. It’s a truly humbling sight.

Heading west, we watched the Colorado River slice through the canyon, as six Californian Condors circled serenely overhead. This is one of the few places on earth you can still see this rare bird in the wild.

The next morning, a helicopter ride over the canyon gave me my very own bird’s-eye view, and even though I’d looked at little else for the previous 24 hours, the sight of the canyon as the chopper dropped off the edge of Kaibab National Forest down into the valley literally took my breath away. It’s incomparable.

After that we had just a few hours to get our kicks on Route 66 and check out the Hoover Dam before returning to Las Vegas.

Back in the city, I swapped the hiking boots for heels and hit the strip.

I grinned like a child as the Bellagio’s dancing fountains performed to Elvis’s Viva Las Vegas, and was able to visit the Pyramids, Paris, Venice, New York and some of the world’s most famous casinos, all in a single evening.

But despite the glitz and glamour, it’s the glowing red walls of Zion, of Bryce’s other-worldly spires; of Monument Valley’s proud monoliths, and the awesome, ever-changing sea of stone that is the Grand Canyon that remain foremost in my mind.