How about the New Zealand Christmas Tree? (Metrosideros excelsus). The Maori name is "pohutukawa".

It's a coastal tree, evergreen with a dense canopy, 20' - 30' height, spread 25'. It is tolerant of drought and salt air, fog and wind, and disease and pest resistant.

It has dark green leaves with a silvery underside and beautiful red flowers in early summer in California. (In New Zealand--southern hemisphere--it flowers in winter, hence the name Christmas Tree). It is widely available in California nurseries and can be bought as a specimen tree. Different color flowers are available:

Red flowers = "Fire Mountain", "Parnell"
Pink = "Pink Lady"
Scarlet = "Scarlet Pimpernel"
Yellow = "Moon Maiden"

Here is a picture of this tree in San Francisco.

Here is a link that might be useful: Metrosideros excelsus

How about Stenocarpus sinuatus, the Queensland Firewheel Tree. Grows very slowly to about 30' with a 15' spread, evergreen with very little leaf drop, neat flowers. Might need more water than you are willing to provide.

Or Arbutus 'Marina'.
Or a non-fruiting Olive tree.
What about Agonis flexuosa 'After Dark'? Neat burgundy leaves, smaller than the species.
Maybe Prunus caroliniana, Carolina Laurel Cherry,
Or Prunus lusitanica, Portugal Laurel,
Or the Califonia native, Prunus ilicifolia lyonii, Catalina cherry, which is like a big dense Camellia shrub without the camellias, 20', lives very well on winter rain alone.

Pacific Wax Myrtle, Myrica californica, another native, nice and dense.

If you can control the Eugenia psyllid, or if it is under control in your neighborhood, and someone is willing to do some sheering, Syzygium paniculatum 'Monterey Bay'. Nice and dense, that one.

Don't overlook large shrubs when considering a small to medium tree. Lots of good dense foliage possibilities and just as fast as a small tree.

For more tree ideas see "Ornamental Trees for Mediterranean Climates"

Here is a link that might be useful: Ornamental Trees for Mediterranean Climates

Although erythrina is somewhat decidous, but has bright red flowers at such times, it grows well near the coast - also called coral tree.

For a fruitful tree - my vote goes to macadamia. It is well-behaved, and produces several crops of very fine nuts each season. It has lovely plumes of pink flower bracts prior to fruit set, and a nice tree to look at from a picture window.

Just my 2 c's.

Bejay

I'll cast a second vote for Metrosideros. In San Diego on Point Loma it blooms just about year round and is neat and pretty and attracts hummingbirds.

Fern pine (Podocarpus gracilior) is a nice, manageable screen tree too, but without the flowers. It can be maintained in any size.

Consider a coast live oak (Quercus agrifolia) which is quite slow growing and will not exceed 20-30' in your lifetime or that of your grandchildren. When young, it can grow quite "fast" (ours is 10' in 5 years). Casts dense shade the year round. A major hangout for butterflies and other critters.

Another possibility is the mainland holly-leaved cherry (Prunus ilicifolia). As a tree it never exceeds 25', and is slow-growing. The shiny leaves are attractive year round, and the cherries are favored by birds. Attractive tiny white flowers in spring are a magnet for all kinds of flying critters.

Slow-growing native trees will never buckle your sidewalk or the driveway. It's those water-guzzling trees on regular irrigation that are usually at fault.

Here is a link that might be useful: Holly-leaved Cherry