All times are a suggested minimum. One can spend a lot more time in some of these places...
* Yellowstone, Grand Tetons
- Yellowstone is very unique. A good variety of things to do and see. Crowded. 2 days.
- Grand Tetons: Spectacular. Good hiking. 1 day.
* Rocky Mountain, Dinosaur
- Rocky Mountain: very nice. Nice drives and hikes. 1-2 days.
- Dinosaur: also includes some nice desert scenery and historical sites. 1 day. Kind of far from things...
* Glacier and up into Banff
- Glacier: Spectacular. Nice drives and lots of hikes. 2 days.
- Banff (+Jasper & Yoho, Canadian Rockies): Spectacular squared. (See Glacier first--otherwise it will be anticlimactic.) 2 days driving. Lots of hikes too.
* Olympic, North Cascades, Ranier
- Olympic: very nice, mountains, rainforrest, and shore. 1-2 days.
- North Cascades: haven't been there.
- Ranier: very nice: drive and some short hikes from Paradise: 1 day. Mt St. Helens is close by.
- Also don't miss the Columbia River Gorge.
* Mesa Verde, Canyonlands, Bryce, Zion
- Mesa Verde: nice Indian dwellings and artifacts: 1 day min
- Canyonlands: spectacular. Drive + short walks min 2 days (add Arches, 3 day min.) Also add Dead Horse State Park.
- Bryce: very nice--rock formations and some short hikes. 1-1.5 day min
- Zion: very nice--rock formations, walks, and some short hikes 1-1.5 day min
- Natural Bridges, Goblin State Park, Grand Staircase-Escalante, and Capitol Reef are in this area. All are worth visiting.
* Grand Canyon, Petrified Forest, Rainbow Bridge
- Grand Canyon: Spectacular. 1-1.5 days S Rim. 1 day N Rim. Add a full day hike down into the canyon.
- Petrified Forest: nice. small. .5-1 day
- Rainbow Bridge: Nice, but will take a full day to visit (boat trip or multiday desert hike). I found Lake Powell depressing--a beautiful canyon, drowned.
* Yosemite, Sequoia, Death Valley
- Yosemite: spectacular. Valley crowded. Nice hikes of various lengths. 1-2 day min.
- Sequoia-Kings Canyon: the big trees are amazing. (Also groves in Yosemite, Muir Woods)
- Death Valley: never been...
* Mount Rushmore, Crazy Horse, Devils Tower
- Mt Rushmore: ok. an afternoon.
- Crazy Horse: never been
- Devil's Tower: never been
- Don't forget Wind Cave, Jewell Cave, and the Badlands. (I'd skip Rushmore and Crazy Horse if time is tight.)
The desert Southwest stuff is best visited in March, April, and May--my first vists were in August--temps up to 113 or so... The northerly stuff is best visited late summer (eg late July and August) so the snow has a chance to melt off the roads and trails. The snow threatens to return in Sept or so in the higher or more northely locations. Some roads are not plowed, except to clear them in spring.
You are likely to need reservations between Memorial and Labor days--too many other people enjoying the parks...
Doug