Agapanthus?

Or use a plant with silvery-blue foliage

Here are a few more for you to consider assuming that they will thrive in your climate zone;-

Rosemary;- An aromatic evergreen culinary herb. I would suggest creeping or prostrate varieties.
China Aster;- Blooms in late summer to fall. Flowers are also great for cutting.
Tropical Salvia;- It produces spikes of flowers from spring through fall which really attract the
hummingbirds attention.

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Ankrara's Hobby Corner

Would blue plumago do well in your area? It does great here in coastal Texas. They also have a white variety.

I just came back from vacation in San Diego, and the hillsides are a solid mass of blue - Texas bluebonnets - just STUNNING! Would these work for you?