I would love to help you out. I do not see your picture-can you tell me what area of the Southwest you live in? Thanks so much! Deana

How about something like this? Ellis Modern. Has the block look http://www.modplanters.com/products/ellis-modern-rectangle-planter-box

Lowes garden dept. has huge selection of succulents,some are even already planted with mixed assortments,you could put two matching mixed baskets on the ends then a few larger types with perhaps some Rosemary in middle so you get a variation of heights,colors,textures,size of leaves,even smells and with adequate sun and water would even bloom,then in fall some varieties would change color. Some are even trailing so they would spill over the sides creating even more drama. It would be ever changing depending on time of year and season,it would look beautiful