You don't say where you have already been so I'll start East of Flagstaff.
Along I-40 going East you can stand on the corner in
Winslow Arizona and visit
Homolovi Ruins State Park. Then there are
Meteor Crater and
Petrified Forest National Park, Just South of I-40 going toward Grants are
El Malpais National Monument,
El Moro National Monument and the
Ice Cave and Bandera Volcano. In Grants, there is the
Mining Museum.
Acoma Sky City is said to be the longest occuppied location in the U.S. They give tours of the pueblo and there is an RV park next to the casino. In Albuquerque, the
Pueblo Cultural Center and
Petroglyph National Monument are worth visiting in my opinion. Santa Rosa is an old Route 66 town and has the
The Blue Hole, and
Santa Rosa Lake State Park which has a nice campground.
Tucumcari still has dinners along Historic Route 66, numerous murals painted on buildings, a dinosaur foundry at the community college and other attractions.
In Amarillo, there is
Palo Duro Canyon State Park and the
Big Texan on Old Route 66.
Hope you have a Great Trip!!!