Great report so far. You have passed through my neck of the woods and I appreciate the nice comments.
Next time through though you should not go through Dumas from Amarillo. There is a nice "backroad" heading northwest from Amarillo to Boys Ranch to Channing and then into Hartley where the road meets up with HWY 87 again. It goes for about 40 miles through the Canadian River breaks and is a little more fun than HWY 287 north from Amarillo.
By the way, every hill you saw from Clayton to Raton are all old volcanoes from the Clayton and Raton volcanic field. You are right though, the scenery out there is spectacular. My dad and I rode through there on our way to Taos, Red River, Santa Fe a few weeks ago.
Have fun and ride safe man.