Always good to plan early, it may take awhile for the right people to find this thread but when they do you will likely be swamped with ideas. I've traveled to the South West on two occasions and missed seeing most of the great places. It is a big area with so much to see and places to visit, seldom boring but time consuming for those that like the outdoor scenery and photography so planning far in advance is a must.
I traveled to New Mexico, Arizona and Mexico last March, took a Southern route at the time because of weather conditions. Members that live in the SW will be more able to tell you what to expect for the time you are traveling as for the weather and temperatures to expect.
When planning this last trip I asked for and received advice from this forum, also searched threads/photos posted from the past that gave me an idea of what I might like to see myself.
I'm an outdoor person,want to visit places with great scenery and wildlife, hate crowds, heavy traffic, dislike cities, so having said that I'll just mention a few places that I've enjoyed tremendously.
In New Mexico, the western half, all along Int 25 North to South and staying either on it or to the West.Favorite places I've been to, the drive on hwy 14 through Madrid. The Sandia Peak, Albuquerque area, Bosque del Apache. As of this time I've not been North of Alb far but have heard it is beautiful around Santa Fe and Taos.
In Arizona, Chiricahua Nat Mon,L.Montezuma, Dragoon Mts, Sabino Canyon, Petrified Forest, Painted Desert,Grand Canyon West,Sedona, Flagstaff. I did not spend much time in Sedona, although beautiful, too many people competing for a place to set up their tripod or hire a pink jeep to ride in so I moved on quickly.
Utah, I traveled I 15 to I 70 than East, this is a beautiful area and I missed most of the attractions because I was out of time. Should have allotted much more time for this area, big mistake on my part and must go back if I get the chance.
Colorado,anywhere West of Int 25, had one of my all time best vacation days in Georgetown. Also like Rocky Mtn Pk near Estes Park CO.
Nevada, I've drove from Laughlin to Las Vegas,stayed a night in Vegas, glad I got to experience it but sorry I have no desire to go back. Should have spent my time in Utah, somewhere like Moab.
Wishing you safe travel, enjoy your vacation to the SW U.S. and when some of the locals find this thread you will have many more ideas. If you have any questions on areas I've mentioned feel free to PM me and I will try to be of help.