Maybe try Garden Web California forum.

Araucaria heterophylla

Albizia Julibrissin

Crepe Myrtle 'Natchez'

You will need a tree with a pretty compact canopy for that size space. Avocado or citrus could work, depending on selection. Possibly a Japanese maple if not under any watering restrictions. Not sure you get enough summer heat for the crape myrtle to bloom well - check to see if any local ones. And the other two noted will just get too darn big for that space.

Try the variegated lemon tree. Pink lemonade/eureka

The Bronze Loquat (non-fruiting type), Eriobotrya deflexa, makes a good small shade tree, evergreen. It does help to have a skilled arborist shape it in its youngest years for the most beautiful multi-stemmed form, but at small sizes it is not a great expense. A neighbor has two trios of them, all multi-stemmed. They look beautiful year round and provide good shade.

Citrus is also a good idea as they are beautiful trees, quite apart from the fruit. There is a lot of climate variation in the Bay Area, check to see what Citrus is appropriate for your specific area.

Avocado produces very dense shade and have the potential to get quite large 30-40', however they take very harsh pruning. Root system is sensitive and should be shaded and not compacted by being walked on.

Look also at the Sunset Western Garden book section on "patio trees". Most any library in California has that book if you don't want to buy a copy.

A medium or large shrub can be limbed up as a small shade tree as well, so don't think you have to limit yourself to the "tree" section of the garden center.

I am in Cupertino (not the hill side; but in the valley).

Does Bronze Loquat/Citrus types/Avacado have invasive root system that can affect the house foundation? The tree will be 11 feet from wall. So far it looks there will be no issues, but I like to know your experience.

hoovb,

Thanks for the book reference; I will check it out. I totally missed the idea. I prefer trees instead of shrubs since the tree can also provide some privacy to my second floor window.

To all,

Thanks for the ideas. I appreciate it.