Yellowstone or Zion?

Neither is a place to swim, but Zion at least gives you a proper dip. Sand Hollow reservoir, about half an hour away near Hurricane, has red-sand shores and water warm enough from June to September, while the Virgin River in the park is only for wading.

Yellowstone has nothing similar. The lake stays dangerously cold even in August and the thermal pools are off limits, so the nearest thing to a swim is a quick summer plunge in the Firehole River canyon or a soak in a commercial hot-spring pool outside the park.

Both treat eating as fuel, but Yellowstone has a regional flavour. You can eat bison burgers, elk sausage, trout and huckleberry pie in the historic lodge dining rooms and in the gateway towns' steakhouses. The catch is distance: park kitchens close early and meals are far apart.

Zion has no regional dishes. What it does have is one short strip in Springdale at the park gate, with early cafés for hikers and a couple of dining rooms with canyon views. Many visitors simply stock up at a supermarket in Hurricane or St. George.

Yellowstone has more history to show. As the world's first national park, it has the great log-and-stone Old Faithful Inn, the Roosevelt Arch and the army buildings of Fort Yellowstone at Mammoth. The Buffalo Bill Center of the West in Cody, with its Plains Indian and Western art collections, is a real museum worth the drive.

Zion's human story fills a few hours. It takes in the Human History Museum, scattered rock art, the galleries cut into the 1930 tunnel, the Grafton ghost town and the pioneer temple in St. George. These are pleasant stops, but none compares with the Cody museum.

Neither has nightlife, and both are early-to-bed places. Yellowstone's evenings mean a lodge lounge, a ranger talk or a saloon in West Yellowstone or Gardiner. Zion's mean a patio drink in Springdale under very dark desert skies before a pre-dawn start on the trail.

Both are among the great natural landscapes, but you experience them differently. Yellowstone is a vast volcanic plateau where much of the wonder is close to the road: Grand Prismatic, the Mammoth terraces, the Lower Falls of the Yellowstone River, and grizzlies and wolves seen through a scope at dawn. It is a place for watching, spread over huge distances, with the Tetons just to the south.

Zion is vertical and physical. You wade the Narrows between walls a few metres apart, haul yourself up the chains of Angels Landing or go canyoneering through slot canyons. It also has the quieter Kolob Canyons, and Bryce's hoodoos are about two hours away. Choose Yellowstone for geysers and wildlife, and Zion for hiking you will remember.

Day trips matter little in either place, and both demand long drives. Yellowstone's outings are to Western towns: Jackson with its galleries and wildlife art museum, Buffalo Bill's Cody, Bozeman, the gold-rush streets of Virginia City and the high Beartooth Highway to Red Lodge.

From Zion, the best spare days are spent in other canyons, Bryce above all. The towns are smaller stops, among them Kanab's film-set heritage and the ranch fort at Pipe Spring, and Las Vegas is too far for comfort.

Both suit outdoor families about equally well, in different ways. In Yellowstone the show comes to the children: eruptions on a timetable, bubbling mud and bison by the road. The price is hours of driving and constant watching near the hot ground and the animals.

Zion is less tiring to manage. The shuttle ends the parking hunt, the Pa'rus Trail can be cycled, and the Riverside Walk ends in a river to paddle in. Its famous cliff-edge hikes and summer heat rule out much of the rest for small children.

Yellowstone runs on the car. There is no public transport in the park, and every sight hangs off the Grand Loop Road, a slow, twisting figure-of-eight of about 230km. Bison stop the traffic and car parks fill at Old Faithful, so getting from one sight to the next can take hours. The airports are an hour or two outside the gates.

Zion is far simpler. In the busy months a free shuttle runs up the scenic drive to each trailhead, and another links Springdale's hotels to the entrance, so the car can stay parked for days. You need to drive only for Kolob Canyons, the east side or Bryce, and the roads there are good.

Shopping is an afterthought in both. Yellowstone's gateway towns sell fly-fishing tackle, and Cody and Jackson add cowboy boots, hats and wildlife bronzes. Springdale's outfitters rent dry suits for the Narrows beside galleries of Native American jewellery and pottery, and St. George adds outlet stores.

Zion is easier on the wallet. Once you are there, hiking and the shuttles cost nothing, and Hurricane and St. George are close enough to make cheap motels and self-catering a real option.

In summer, Yellowstone charges a lot for ordinary lodge rooms and motels, and Jackson is notoriously expensive. Fuel and a hire car add to the bill over the long distances. Campgrounds, picnic lunches and a September visit help, but the gap remains.

Zion has much more on stage. In the warm months, Tuacahn stages Broadway musicals in an open-air amphitheatre against red cliffs near Ivins. The Utah Shakespeare Festival in Cedar City runs a respected repertory season into the autumn.

Yellowstone's offer is more Western than theatrical. It has the summer evening rodeo in Cody, family musicals in West Yellowstone and the Grand Teton Music Festival's classical concerts at Teton Village, with campfire ranger talks inside the park.

For pampering, Zion is the better choice. A handful of destination spa resorts near Ivins offer yoga, treatments and guided hikes, and several Springdale lodges have spas and pools with canyon views.

Yellowstone offers something else: an evening soak in the open-air hot-spring pools near Gardiner and in Paradise Valley, with mountains around you. Real stillness comes from timing, either an early morning by the lake or a visit in September or October.