We live 25 miles south of Tucson and were just over in Indio for three weeks!
Have used the 85 for many years to bypass the mess on Phoenix! And they have improved the road immensely; some places it it is 4 lane divided like driving a freeway.
I would not consider any other route. If you are not going to do it in one day I recommend Augie's in Gila Bend or Leaf Verde in Buckeye - reservations for both. Have been them several times.
Be safe.
(Tucson Jim - when are we going to do coffee?! :-) )