We will be traveling in our car from Denver to Dallas. Just wondering if there are any interesting spots to visit along that route. Have been doing some research on my own and not finding a lot of interest. Thank you

The town itself wasn't terribly interesting, but in Bartlesville OK is the Price Tower, Frank Lloyd Wright's only skyscraper. It's a hotel, restaurant & art center.
https://www.pricetower.org/
Of course, Santa Fe is kinda on the way.

Exactly which route are you taking? How much time do you have for the drive?

What type of things do you find "interesting"? Palo Duro Canyon (about a hour's drive from Amarillo, TX) can be described as "interesting" and there are dozens of State and National Parks & Forests along the route that you might find "interesting". Would you be willing to detour from the most direct route? If do, consider visiting Santa Fe, New Mexico.

We are interested in everything. Love history the most probably. Route isn't set in stone as we are retired. Have already been to Santa Fe and Albuquerque.

Well, if it were me and I had no time constraints:

I'd get the hell out of Texas, then get off the interstate and work my way north via Angel Fire and Taos, New Mexico, then head into Colorado, possibly towards Alamosa, maybe spend some time at the Sand Dunes, or towards Pagosa Springs, Durango, Telluride, Ouray, Black Canyon of the Gunnison, Salida, Buena Vista and maybe Breckenridge, Frisco or Silverthorne, before heading east to Denver. Circuitous and time consuming? No doubt.

How you're not finding anything of interest tells me you've either not considered getting off the interstate or you're not looking very hard. There is absolutely LOADS to see and do en route.

EDIT: I read this as Dallas to Denver, but I'd do the same, just in reverse.

Earlier this year, we drove from Oklahoma City to Denver and made the following stops (in reverse) on the way home.

Capulin Volcano National Monument
Quick photo stop at Cadillac Ranch in Amarillo
Palo Duro Canyon State Park
Oklahoma City National Memorial & Museum. While it's not the most direct route to Dallas, I highly recommend a visit.

A visit to the Paint Mines Interpretive Park in Calhan, CO and Bent's Fort in La Junta could also be done along the way.