I'm excited for you, Don. You may wish to plan your trip in advance, however, because the distances are so vast out west. Yellowstone NP is brilliant - a gigantic ancient volcano - and well worth the time, but make reservations well in advance. Yellowstone and Jackson Hole are far to the north if you want to see the Grand Canyon. If I may, allow me to make a few suggestions, for what its worth. Here's a southerly route to consider:
Take I-70 west from Denver to Grand Junction to see Colorado National Monument. Take highway 50 south to 550 where the San Juan Mts begin, and the Million Dollar Highway goes to Silverton. Hope you like heights. At Durango, head west on hwy 160 and stop at Mesa Verde NP to see the cliff dwellings. Continue to hwy 491, go north to hwy 191 in Utah. If you wish you can go north and see Arches NP and Canyonlands, or take a left and turn right on hwy 95* going west over Glen Canyon to hwy 24 through Capitol Reef NP to hwy 12 south to Bryce Canyon NP, my favorite park. On the way notice "Escalante Canyons" on your map, which is where I recall going over a section of highway called "Devils Backbone" where the road shoulders become sheer cliffs without guardrails. Great stuff. The wife was terrified. At hwy 89 go south to hwy 9 which will take you through Zion NP; you drive through a granite mountain down to the valley. The north rim of the Grand Canyon and Las Vegas are not too far from Zion.
That's it. The only other suggestion would be to go north up hwy 395 on the east side of the Sierra Nevada mountains, rather than through California's central valley. It's beautiful, and you can enter Yosemite NP from the east, by Mono Lake.
*Perhaps continue south on hwy 191 to hwy 163 into Monument Valley where John Wayne shot so many westerns. There's a scene in Forrest Gump where he stops jogging on hwy 163 just north of the valley.
Hope this helps.
Ken