Just got back from there. Cold as a ..... Our water froze several nights when we camped in Chaco Canyon. I would put that as a must stop on your trip. It's out of the way, far from conveniences such as showers, but definitely worth the time. If you're into Indian culture, allow yourself at least 3 days there. I shot about 35 images in 8x10 B&W there. I'm about halfway through developing my images.
If you go to Santa Fe, give Bostick and Sullivan a call and see if they have time for you to visit. They are fine people and they have plenty of material to open your eyes to the possibilities of alternative processing. (And they make the best contact printers on the market.) But beware of Santa Fe; time evaporates quickly there. Go through the Abiquiu valley where Georgia O'Keefe found many of her subjects. We only stopped for a few digital snaps but the memories of that drive was wonderful.
We also went to White Sands simply because I had to take some obligatory dune photos. It's a long ways down to there, but the drive from Cline's Corner (highest gasoline on the trip at $2.70 regular) to Alamagordo through Corona is wonderful.
But my favorite drive was from Milan to Silver City. The quaint town of Quemado is worth a lunch stop. The drive up to Mogollon is pretty intense with twisty single lane road and blind curves. Downtown Silver City, like Santa Fe, can suck a lot of time but there are some good restaurants there and a great coffee shop with wireless. The drive to the Gila Cliff Dwellings is a long, twisty trek, (allow about 90 minutes) but it's a great area.
My regrets are not doing more of the great hiking trails at Chaco, not going up to Bisti after we left Chaco, and not taking more roadside fotos. We'll do that next time, and make it to Taos as well.
Good luck