Sounds like a great project to do over the course of a few years! A colleague, Maureen hasn't seen your posting yet I presume, but I'll ask her if she can give you more specifics for your garden as she is also in California and more familiar with drought tolerant species out West.

My reaction is to do large, pleasing sweeps of groundcovers that will naturally choke out weeds and be drought tolerant. Various succulents, including yucca, clusters of large and small agave and sweeps of red, yellow and green-leaved sedum and sempervivum could be masses and then accents of South African dryland bulbs and Mediterranean springtime bulbs could be planted. Of course, the exact species of plants to be the foundation of this dryland creation will depend on your winter cold and soil. If you receive little frost, many more subtropical succulents and California natives could be played with, perhaps even some dryland scrubby palms!

Since you mentioned flowers and fragrance, might I suggest, that in the overall scheme, that you have one area (the CLOSEST to your house or the garden spiggot/hose) that you gear towards drought tolerant perennials and cutflowers. Let the vast expanse of this planting be low on maintenance and water use, but a convenient corner could have a higher concentration of more traditional flowers that you will enjoy without having to walk as far.