I assume you'll be on the I40 when passing thru Arizona, East to West.
Roughly between Gallup & Holbrook is the Petrified Forest.
Whilst in Eastern Arizona, La Posada in Winslow is a treat for overnight. A restored Harvey House from the "wayback" with a great restaurant.
http://laposada.org/A loop North on the 87 allows passage thru Hopi & Navajo land; First & Second Mesa are a treat.
From Second Mesa the 264-160-89 south gets you to Cameron, another nice overnight spot.
From Cameron you access the fabulous 64, which takes you West along the South Rim of the Grand Canyon to the El Tovar, famed in lore & legend. (
https://www.grandcanyonlodges.com/lodging/el-tovar-hotel/ )
The 64 goes South to the 180 back to Flagstaff. Good accommodations and a great time to visit the Lowell Observatory in town where Pluto was discovered by Tombaugh. (
https://lowell.edu/visit/ )
I HIGHLY recommend a loop South from Flagstaff on the 89A, thru Sedona, Cottonwood, Clarkdale, to Jerome for lunch (
https://www.oldtownredroostercafe.com/ ) and onward to Prescott for the night. (
https://www.hassayampainn.com/ )
From Prescott, the 89 takes you back up to Ashfork & the 40, where the 66 diverges a couple miles out of town.
West of Ashfork you get to Seligman where you find Delgadillos Snow Cap, a local treasure. (
https://www.atlasobscura.com/places/delgadillo-s-snow-cap-drive-in )
Continuing on Westward on 66 you'll get to Peach Springs and the Hualapai Lodge, another nice place to spend a night & find a meal. (
https://grandcanyonwest.com/welcome-to-hualapai-lodge/ )
From Peach Springs you get to Kingman. Thread your way thru town past the "Emerald Pools" (waste treatment ponds) and pick up 66 through the Black Mountains to get to Oatman, Arizona. (
https://www.travelawaits.com/2558142/oatman-arizona-best-things-to-do/ )
From Oatman head South on the ancient 66 tarmac to arrive at Topock Arizona. (
https://en.wikipedia.org/wiki/Topock,_Arizona )
About 6 miles out of Topock on the 40 you'll be able to take a jog over to the 95 and take that North on into Needles.
The 66 is accessed by taking 40 North about 10 miles to the 95 exit. The 95 takes you towards Las Vegas. About 8 miles or so on the 95 you'll find the "Goffs Road/66" turnoff at Arrowhead Junction. This will carry you all the way to Ludlow where there is fuel.
The 66 has a break at Ludlow, where a new section on the East side of the freeway carries you about 5 miles to an overpass where you pick up the original road again. Br aware this bit is very rough, so take your time to Newberry Springs where you'll find fuel. The rest to L.A. is mostly just bits.
Good Hunting - ACR -