How old are the children? What route are you taking to Yosemite? From there are you returning to Tennessee? With the children I would suggest skipping Death Valley/Las Vegas and instead, work your way to SW Colorado along Hwy 160.
Yosemite via 120 to Lee Vining, CA on Hwy 395. Stay in Lee Vining and visit Bodie Ghost Town. From Lee Vining, take Hwy 6 to Ely, Nevada to I-70 east.
You could then work in some of the fantastic Utah national parks - Bryce, Capitol Reef, Arches. From Arches take UT191 south to 491 to Cortez, Colorado and visit Mesa Verde Nat'l Park on Hwy 160. Take the ranger tour for the old ruins. Kids love it. Then go east to Durango, CO and visit Silverton, CO. Continue east on 160 to Pagosa Springs and soak in the warm pools.
Pick up 84 south into New Mexico. Visit Bandelier Nat'l Monument - old ruins and work your way to I-40 east for home.
When going out to California try to work in the Grand Canyon, AZ
These are much 'cooler' places than Death Valley/Las Vegas - both in temperatures and things to do.
I might add it's a very long trip to Yosemite. How much time do you have for this trip?