I-40 From Tennessee to California

You're going to see a whole lot of nothing from Texas to Arizona! It's been a while since I've been on that road, but I love driving and seeing a lot of nothing. You do pass by or through a lot of things. Monument Valley, the Meteor Crater, Grand Canyon, etc.

What he said-----lots of NOTHING on that road.

Someone who I have forgotten once said the interstates allow you to go from coast to coast and never see anything and there’s a lot of truth in that. I’m sure there’s much to see in AR, some around the OKC area, NM and AZ. But you’d have to get off I-40 to see most of it. If you stick to the freeway I can’t think of much until you get to the places mssmith1199 mentioned, though I’d add the Petrified Forest, Painted Desert and maybe Sunset Crater NM to it.

So, lots of things to see and do along I-40. However, not knowing your interests this may or may not be of any help.
Working our way East to West.....
Nashville. Lots to do and lots to see if Country music holds any interest. I am not a country fan but had the best time at the Grand 'ole Opery.
Memphis. Graceland. Interesting to me. Maybe not to you.
Little Rock. Clinton library (called something else) again, if you are interested.
Ft. Smith, AR. Fort Smith. Maybe more!
All through OK, lots of "changes" to visit a number of Indian Casinos.
OK City, OK. The Murrah building bombing museum is EXCELLENT! It could be a bit disturbing for kids (I don't know, but it's very descriptive!).
Also in OK City is the Cowboy museum and is a MUST SEE. It takes a very long day to see or can be seen better with a 2 day visit.
Amarillo, TX. The Big Texan Steak House. Eat more food than 5 people should and get your meal for free! You aren't going to do this but it's a great stop with good food and a "been there, done that" stamp.
Albuquerque, NM. Can you be here in Oct!? If so, plan to stay for at least a week for the Balloon Fiesta. If not, plan to visit the Balloon Museum. You might also find one or two excellent casinos here. If you don't mind a detour, check into the VLA (Very Large Array) antenna farm in Socorro, NM to see if they are doing anything open to the public while you are in the area. We happened upon an annual event with scientist led tours which left me feeling very stupid but extremely curious. It was a great day.
Between Albuq and Flagstaff, AZ you will pass through the Painted Desert, the Petrified Forest and Meteor Crater (do not drive past Meteor Crater).
Flagstaff, AZ. Plan to visit Lowell Observatory. Check online for the various activities available during your visit. There are day time viewings of the sun and evening viewings of the planets as well as historical information during the day. Lowell is the place where Pluto was discovered.
Stay at the Black Bart RV Park and have dinner at the Black Bart's restaurant. Have the Prime Rib and enjoy show tunes performed by your wait staff. They are all corral students at the local college and just plain fun.
Next stop, Williams, AZ. Stay here and take the train to the Grand Canyon. You can do it in a day (in a hurry) or plan an overnight at a hotel at the Canyon and return the next day. Awesome! Even more awesome is to detour your trip to include actually going to the Grand Canyon with your RV so you can spend several days exploring this amazing part of the US.
Kingman, AZ. Nothing to do here.....However, less than 100 miles N of Kingman is the Hoover Dam, with a very cool side trip to VEGAS BABY! If you go to the Hoover Dam be sure to take the insiders tour and not just the "standard" tour. You go inside the dam and get much more history and detail. It's worth going out of your way.
OK, finally, from there West there is not much that I find interesting until you get to the Presidential library in Simi Valley. Just a bunch of big city stuff you wish you didn't have to deal with.
What more can we discuss? You should have a terrific experience and don't let anyone tell you that there's nothing to see along any road in this great Country of ours!

Southwest of Little Rock Arkansas is Hot Springs. Lots to do there. Very interesting: bathhouse row, gangster museum, mountain lookout tower. We like Catherine's Landing RV Resort on Lake Catherine. Or Lake Catherine State Park.
Just North of Tulsa in Claremore OK is the J. M. Davis Gun and Historical Museum. Lots more than gun collection.
Near Amarillo TX - Palo Duro Canyon. We liked Oasis RV Park there (no shade)
North of Albuquerque is Taos and the Enchanted Loop. Very beautiful scenic drive.

I can't give you any suggestions for attractions to see as we pretty much drove through with one night stops from NV to AL in February. However if it works into your schedule there was one RV park that was a stand out and one that I wish we could have spent more time at.

It is Tom Sawyer's RV Park in West Memphis, AR, which is on the west side of the Mississippi river just across from Memphis, TN. It's definitely nothing fancy. We had a river view site, and even though we had to endure a severe thunder storm with tornado warnings, once that passed it was beautiful watching the tugs handle huge lines of barges up and down the river.

And then there's
Cadillac Ranch near Amarillo TX

Just North of Tulsa in Claremore OK is the J. M. Davis Gun and Historical Museum. Lots more than gun collection.

we spent 1/2 of an entire day in there.. so much too see
including the "Surrey with the Fringe on top" from the movie

also in Claremore is the Will Rodgers museum, two things, one town

Just pass the arkansas /Okla line is lake tenkiller about 15 miles north of interstate, very wonderful place to visit i choose to live there... you wont be disappointed with view and food. several state parks and lots of corp of engineer camp grounds.

Bill also north of tenkiller is Tahlequah, "cherokee nation" they have villiage and museum /casino , Native american stuff interest me plus i like to gamble..