The design of the project should evoke a relaxed atmosphere while also meeting your requirement of providing a drought-tolerant garden. Crushed gravel as a ground cover helps reduce moisture loss and acts as an alternative to mulch. I have chosen plants that have been listed as being drought tolerant in your area while still providing lots of visual interest with flowers, colours, scents and foliage. Loosely placed paving slabs create the paths and interspersed slabs amongst the planting will blurr the line between path and the rest of the garden. this should invite the observer to walk between the plants and experience the garden in a different way. The plants are loosely spaced allowing for gravel to "flow" between them adding to the relaxed setting.