HI Cameron... I am curious, are you looking for perennial herbs or annuals? Are you considering herbs as ornamental or will you be using them in cooking or medicinal uses?
Rosemary would be a good choice for a perennial that will endure harsh conditions. Another that likes to be high and dry is lavender. I've never had luck with thyme and thought perhaps it didn't like the heat.
I also have a bay tree in a large container which I use in cooking. Bay could grow a bit large in ground although it might provide some needed shade for your other herbs.
When you mentioned drought tolerant, will you be able to provide water under extreme drought conditions? Even though most herbs don't require rich soil, they do require adequate moisture
Some herbs like cooler weather. Dill, chives and chervil are growing right now for me.
Some herbs will reseed although they are annual. I start most of the annual herbs from seed by wintersowing and then transplanting when the soil has warmed enough.
I'll have to do more thinking on drought tolerant herbs and hope others will weigh in too.
