There are thousands of daylily cultivars. I don't know about fragrance, but Stella de Oro is perhaps the longest blooming daylily variety.
Daylilies are moderately drought-tolerant,but extra watering will help prevent leaf scortch and should keep them blooming. Also well-drained soil, that is high in organic matter, along with several inches of organic mulch should be helpful.

Here is a link that might be useful: Desert Gardens