IT IS EARLY October in Salt Lake City and the blush-and-glow of Japanese maples, while not as pompous as the fall foliage along the East Coast, is a sight for sore eyes. The leaves cling to straggly branches, and sunsets to the horizon. Flaxen-haired aspens teeter in the wind. Many roads beckon. To the north-east loom the Wyoming Rockies and the geothermal surrealism of Yellowstone National Park. To the south, but alas, a day’s drive away, the Colorado River carves, as it has done for millions of years, at one of the most magnificent red rock canyons in the world. We vacillate between the two, but we can choose neither. Which is to say we choose both. America’s oldest national park, straddling the states of Wyoming, Idaho and Montana, is…