Nothing works like annuals: A blast of color, then... death. Anything that is showy and blooms with lots of color seems to require a lot of labor. And water, and fertilizer.

I just planted some "Little John" bottlebrush for long-lasting color. After establishment, they have relatively low water needs, and can stand up to the wind. Their dark red blooms and blue-green foliage looks good with pink and blue. Agapanthus (blue), rhaphiolepis (pink), Mexican primrose (pink) and ceanothus (blue) are some possibilities, although the Mexican primrose is invasive. You can also plant irises, since they have relatively low water needs, but they need division every few years. Some are reblooming and/or everblooming- especially the small purple ones. True geraniums are lovely too. Planting bulbs can give you a blast of color in the spring: Asiatic lilies grow well here and come in pale pink. Ivy geraniums are exceptionally floraliferous, but they take quite a bit of water.

How does Iceberg rose do in your climate? The city's "Brilliant Pink" icebergs are knocking my socks off this year.

Good luck, and let us know what you settle on.
Renee

I'm in zone 17 but that's a very large zone (I wish Sunset would break this one up someday). I'm 25 miles from the coast in the Oakland hills, so I get the fog but more sun than you do. The following are all ones that have done well in my shady areas (of which I have a lot). Many of them have variegated leaves. I love variegation and because most annual flowering plants have uninteresting leaves save for coleus, I think it adds a brightness to shady beds.

You need to think in terms of foliage: the contrasts of texture, size, shape and color. That’s what gives you year-round interest, allowing you to ramp up the drama with seasonal changes in bursts of flowering.

Decide what overall shape you want, especially if this bed is viewed from a distance as well as close-up. Medium-height center, surrounded by low growers? A taller center for more striking contrast with lower undergrowth? You might envision your circle design as the spokes of a wheel – the outer circle of plants alternating between evergreens and annuals.

Strong winds mean that if you want a dwarf tree or shrub to act as the 'backbone' for your circle, it needs to be one that develops a strong trunk so when properly staked, it will grow nicely upright without a 'wind bend' to it. Note that using a tall-growing center plant may mean even more shade for the plants on the leeward side.

I’d use a nice Japanese maple, like ‘Emperor 1’ for its beautiful dark red leaves and graceful layered upright shape, for example. Or a Rhamnus variegatus, tall and narrow. The Rhamnus (buckthorn) is evergreen, with white-edged small leaves that catch a lot of light. Both are wonderful background plants that top out around 12’.
'Emperor 1' Japanese maple:

Rhamnus variegata, long view:

Closeup of leaf color (it's above a pelargonium fancy-leaf hybrid 'Vancouver Centennial', but you wouldn't want this one as it has orange-red flowers):

Conversely, you could use something of modest height - say, around 3-6 feet – as the center. A spiky phormium (New Zealand flax), for example: the red/pink varieties are much more modest growers than the larger brown-leaved P. Atropurpureum. If you want an almost perfect round ball instead of vertical spikes, the shrub Lantana ‘Peaches and Cream’ (don’t get the trailer of the same name!) ignores the wind and will flower even in the fog; it gets 3-4’ around but is easily pruned.
'Sundowner' phormium in heavy shade, 3 yrs old:

'Peaches & Cream' shrub lantana, planted atop a concrete wall -- right hand side, just in front of the cluster of blue agapanthus flowers:

With a more open, irregular branching shape in partial sun, 3’ tall evergreen Rhaphiolepsis indica (Indian Hawthorn) ‘Ballerina’, is a dwarf that has lovely pink flowers sporadically through the year, with handsome dark leaves that have a tan underside. Shade groundcovers will live near and under this, such as Stacchys byzantina (lamb’s ears; ‘Helen von Stein’ should be selected if you don’t like the bee-favored flower spikes of the standard varieties) or the gorgeous burgundy Oxalis ‘Charmed Wine’.

Rhaphiolepsis indica 'Ballerina':

Oxalis 'Charmed Wine' (just planted last week):

For sheer unabashed colorful variegation, the fuchsia ‘Firecracker’ is a stunning specimen at 4x2’ that catches the eye even when it isn’t flowering (BTW, these are height x width measurements). Magilla perilla, a coleus relative, might work for you as coastal fogs keep frosts away from your garden. Strobilanthes aka Persian Shield, is another possibility that is even more beautiful.

Fuchsia 'Firecracker':

Magilla perilla:

Strobilanthes:

I love pelargoniums, but many of them are scraggly in shape or flop over. Only a few have shown tight bushy shape, but the labels aren't much help that I've found. You should be sure to select them in flower as some of them have rather strident hues that don’t always play well with others.

This fancy-leaf is either "Skies of Italy" or "Mrs. Pollack". The leaves of both varieties are virtually identical, but one has pink flowers and the other has reddish-orange flowers.

Lower growers could include the 1x2’ mini-trailer Erysimum ‘variegata’, my favorite for beautiful variegated leaves that produce gorgeous spikes of lavender flowers for months on end. Lamium ‘Purple Dragon’ has beautiful silver leaves and purple flowers that really stand out on dull gray days. Even purple variegated sage, the ordinary cooking herb, has nice leaves and surprisingly pretty flower spikes once a year, although it generally only lives 2-3 years.

Erysimum 'Variegata':

Lamium ‘Purple Dragon’:

If you want taller ‘spokes’ alternating with lower ones, consider a mini-rose. They grow much better in the ground than in pots, and come in many colors; they are easily found during the holiday season. Or an azalea: a little acid fertilizer and sulphur will take care of its soil requirements. 1x2’ Brunnera ‘Jack Frost’ has amazing silver leaves and sky-blue flower spikes.

Brunnera ‘Jack Frost’:

I have an unnamed reflowering dark purple iris that has marvelous blue-green sword-like leaves that look wonderful with other foliage and flowers, even when out of bloom. Another remarkable, unusual specimen is the true dwarf canna ‘Pink Sunburst’.

unnamed reflowering dark purple iris - that's a variegated Aucuba 'Gold Dust' next to it, a good shade plant easily kept to about 4x4' with pruning:

Dwarf canna ‘Pink Sunburst’ - all other 'dwarf cannas' seem to be 4' tall. This one is truly only 2' or less:

Lithodora is a magnificent blue low-growing perennial – you might have better luck with it where you are. In my crowded and xeric Oakland hills garden, it can’t seem to establish itself well enough against the more established evergreens. Variegated heuchera ‘Snow Angel’ is a delicate plant that might be worth trying; it’s amazingly floriferous for its size.

Lithodora - this is the dark blue variety; most are a lighter blue:

Variegated heuchera ‘Snow Angel’:

Anyway, hope the photos help you envision some possibilities.

Your yard looks so lovely.
Renee

I'd also second the recommendation for succulents in general, they will be low care, low water, and can give foliage color and blooms at all times of year for next to no care. Just selecting from Aloes alone would give a lot of variety, and single trunk specimens such as A. ferox, A. marlothii, A. thraskii, A. speciosa could be a tall centerpiece, with lower growing Aloes such as A. striata, A. reitzii, A. rubroviolacea, A. cameronii, A. nobilis, A. 'Johnson's Hybrid' as lower growing ones. These aloes bloom at various times of the year, but most on the list are winter to spring bloomers, except that A. 'Johnson's Hybrid' blooms all year round.

Other easy growing coastal species that would be showy yet easy might include Strelitzia juncea, Coleonema pulchellum 'Sunset Gold', Metrosideros collina 'Springfire', Euphorbia characias, E. lambii, Bulbine frutescens, Phormium cultivars, Lavandula stoechas, Erisymum 'Bowles Mauve', Erigeron glaucus, Dudleyas, Cotyledon orbiculata and C. macrantha, Echeveria agavoides and E. imbricata, Tulbaghia violacea and T.v. 'Silver Lace', Leymus condensatus 'Canyon Prince', and a lot of the lower growing ground cover type Manzanitas such as Arctostaphylos densiflorus, A. 'Emerald Carpet' or ground cover type Ceanothus cultivars such as 'Yankee Point' or 'Carmel Creeper'.

You might also include a variety of Aeoniums in the succulent mix, and Aeonium 'Zwartkop' has spectacular black purple foliage, A. canariensis, A. 'Kiwi', A. arboreum 'Atropurpureum', A. undulatum, A. 'Sunburst', A. haworthii. Iceplants such as Drosanthemum, Delospermum, and Oscularia deltoides can also grow thick and low enough to suppress weeds with brilliant waves of color in season with next to no water. Other succulent ground covers that I would highly recommend are Senecio mandraliscae and S. repens.

So even if you were to do an all succulent garden, you could have riotous color equal to any annuals planting, with next to no watering required, and complete wind and salt spray tolerance, and foliage color and/or year round blooms. Throw in a few Echium species such as E. wildprettii and E. fastuosum, and you would be all set.

There are other California natives that are much longer blooming, a Fremontodendron 'California Glory' can easily continue blooming for up to 4 months, the Manzanitas and Ceanothus are more like 6 weeks max.

I'd suggest you look up individual plants on-line, or loook at a book like the EBMUD book, Plants and Landscapes for Summer-Dry Climates, if you want to see pictures and more descriptions, or consult the Sunset Western Garden Book. A visit to Tilden or UC Berkeley Botanic Garden could also give you some better ideas of natives and succulents, and there are also native succulents such as Dudleyas.

I have an A. arboreum 'Atropurpureum' and although I think it's very pretty, it isn't that great as a centerpiece plant, without careful companion planting.

I bow to bahia's judgment as always, he's always offered great suggestions. I didn't think of the wind burn on the Japanese maple - my Sango Kaku is very prone to it, although the Emperor 1 cultivar is not.

I have a number of lavendar stoechas and you need to be careful what you put them with. Especially annuals, as most of them need regular water. L. stoechas, like ceanothus and echiums, really dislike summer water and even with good drainage, it shortens their lifespan.