we are traveling to phoenix from omaha any shorter 4-lane highway shortcuts ( can do 2-lane if we have to)
Best way Omaha to PHX? Southwest Airlines?
I'M JUST JOKING!
I assume you are wanting to do this in the shortest possible time?
I-80 to I-76, Denver, I-25 to Albuquerque and then I-40 to Flagstaff, I-17 to Phoenix is probably the FASTEST route (1478 miles). I do not believe it is the shortest.
My own choice for a fast route would be I-70 from Denver west to US191 in Utah, then south to I-40 or to US160 across the Navajo Reservation. (Almost as fast, better scenery, my opinion only).
I suspect the shortest route is using federal highways (US54 for example) and routing through Salina, Dodge City, Tucumcari, Santa Rosa, Vaughn, Socorro, and into Phoenix via Show Low and Payson. These are good roads, but two-lanes go slower -- significantly slower once you hit Kansas, particularly. Farther west, there are many fewer towns so you can make better time on them. But I have NO doubt this would be a longer trip than the Interstate route I named first.
If this is a wintertime trip, then be careful on the two-lanes and watch the weather closely. If time is critical, you may want to stick to the Interstate routes as you have a better chance of getting to the destination when or if the weather gets ugly.
If you do choose the interstate routing, one good shortcut is to leave I-40 at Winslow, south on SR87 through Payson and into Scottsdale. It is two-lane as far as about Strawberry or Pine, then 4-lane or divided road the rest of the way to Phoenix. It'll cut some time off the trip.