Although not always present on Arizona lots, the number of trees can be a powerful influence on home buying nationally.  In an eastern-U.S. centered study, 18% of repeat buyers and 25% of buyers purchasing a new home said that being on a wooded lot or on a lot with many trees was very important to them. I would guess that in Arizona, that would apply most strongly to lots in the northern half of our state – that are in or near pine forests.
Another benefit is that at least 3 trees strategically placed on a lot can save an average household between $100 and $250 in annual energy bills, according to the U.S. Department of Energy.  Although our Phoenix metro area energy costs are lower than that in many states, the savings caused by shade trees in Arizona should be similar or better than those results.

Sheep under a tree near Dorset, England.

Sheep under a tree near Dorset, England.