|My suggestion: Desert Southwest is very broad. You may want to re-consider the many climates - high versus low desert comes to mind first. It would be helpful.
|Your zip code places you in USDA gardening zone 7A and I agree with you; the gardening zones are not all that accurate because they are so broad. One really helpful resource I've found is Sunset Western Garden Book. It places areas in gardening zones based upon their elevation and proximity to water, both of which can influence plant growth (and winter temperatures). Check out a copy at your local library or Home Depot garden center. The book also lists the best plants for each of the growing zone, which can help you make good landscape choices. Good luck with your landscape!