I would head north from Houston to Dallas, then US 81/287 to connect to I-40 in Amarillo. Take I-40 west will take you thru Albuquerque and Flagstaff, which are much cooler temp wise then using I-10 thru El Paso and Phoenix...also mid-july is Monsoon season in NM/AZ, I-40 route will mean more t-storms/rain while I-10 route dust/sand storms/outflow winds.
Turn offs from I-40 include Sedona (AZ 89A) 25 miles from Flagstaff, Grand Canyon (AZ 64) 50 miles off I-40 via Williams, AZ. If you cut off from I-40 in Kingman, AZ via US 93 will take you to Hoover Dam/Lake Mead and Las Vegas. Cut back to I-40 via I-15 from Las Vegas.
I-15 and 40 meet back up in Barstow, CA where I-40 will become CA 58 which will take you to Bakersfield where you can take CA 99 to Sacramento, you can cutoff in Fresno to go to Yosemite or stay on CA 58 to I-5 which is much quicker to Sacramento...this route avoids LA completely
If don't mind the extra travel you can cutoff from either I-5 or CA 99 to CA 46 west which take you to Paso Robles, which is Cali's "other wine country" minus the snobs from up north then US 101 north to the Bay Area where you can reconnect to get to Sacramento.
After Sacramento, I would stay on I-5 north to Seattle which passes by Shasta, the Rogue River Region, Portland...and so on.
Hope this helps and enjoy the trip.