Took a look at this one at lemuria nursery and, well, not very shady for hot Vacaville.  $65

Geijera parviflora-Australian Willow
Rutaceae Family

Australian native growing to 30' tall by 20'.  The branches are somewhat pendulous thus the name and are 3-6" long.  It casts light shade making underplanting easier.
Flowering is unimportant.  Watering should be deep and infrequent and the plant will do best in well drained soil.  A graceful and tough tree.  Also evergreen.


Australian Willow, Geijera parviflora