Wow, you must love cities! Sightseeing in Houston? LOL, I personally would skip all the cities and spend my time enjoying woods, lakes, mountains, and streams. But each to his own.
I spent a week in Yosemite and it wasn't too long. Yosemite Valley is great, but please be sure to take your Jeep to Glacier Point also; I camped near Glacier Point (at Bridalveil Creek CG) for most of my time in the park and I drove back to the Point several times to sit and enjoy the view or to walk a nearby trail; it's that good.
You have a long spell of drive, drive, drive from Vegas to GA. I would insert a day of relaxation in there, in Arkansas. Either Petit Jean SP (trails, waterfall, scenic overlooks), Lake Catherine SP (cool off in the lake), or Crater of Diamonds SP (get out and dig in the dirt!). But then again, maybe you'd prefer a city like OKC... there's the Cowboy & Western Heritage Museum, OKC Zoo and Botanical Gardens (with butterfly garden), OKC Museum of Art, Bricktown, and more.