Everyone often have a lot of trouble putting together a balanced looking plan with interesting height variations and other design elements.you need to post some pics,They are not too close up,a panoramic shot is good,that show the context and situated and conditions.

It will make a difference what the planter boxes are supposed to achieve and why they're there, so it would be helpful to either see a picture or get a better description of them and their purpose. Are the boxes paralleling the building or perpendicular to it? Are they serving as a location for what's commonly called "foundation planting" or are they flanking the entry walk. What's the layout like? Working with the commercial scale and keeping it low maintenance generally means keeping the design simple and bold. I don't know fernbush other than to know it's "western", but other plants you mention seem likely candidates except purple fountain grass. It can survive some dry conditions but in my experience does not look happy about it. Other grasses may perform better.

Of course the arrangement of the plantings will be contingent on the relationship to windows/views of and out from the building, and whether there is any shade. I'd suggest you consider using some more sculptural plants such as Agave bracteosa and Agave Sharkskin, Dasylirion longissima, Hesperaloe, and smaller growing plants such as Echeveria agavoides, Dyckias, Hechtias and contrasting softer flowering perennials such as Justicia brandegiana or some of the local perennials such as Ruellias and Oenotheras Tulbaghia violacea might be of interest along with Dalea greggii.

Well, as much as I appreciate all of your responses, it appears this is all moot. My boss has someone working in the planters today ... He told me he could tell I felt overwhelmed by the idea of managing the project so he went ahead and hired someone to do it!
This is okay with me, less work, less planning, for something I wasn't earning anything extra on anyway. But I appreciate that y'all were willing to help out!

Well, you can always post the result and we can critically evaluate it :-)

Karin L