I wish I had recommended that you stop in Acoma, New Mexico. It is an amazing place, and the Acoma village on the mesa is the oldest, continuously inhabited city in the U.S. Getting up to it is a easy - coming down can be easy, or you can take the steps carved into the mountain.
The kids would have loved it because they have probably seen it in many westerns! There is also a wonderful little museum on the plateau, with lots of interesting crafts on exhibit.
So many things went right on that trip that I really cannot complain.
As far as "stops," we barely had time to do all we had planned to do. :))