Thanks!

Like the graph paper/pencil route, design software is only a tool and will offer the best results with a good understanding of basic design principles and the plants and their requirements. Some find the pseudo 3-dimensional aspect many programs offer easier to visualize than just plan views created on paper. But you need to be cautious about some of the photoshop aspects, which can distort scale and spacing and alter perspective. And show everything blooming at the same time as well :-)

Personally, I prefer the graph paper and circle template, but then I was trained in hand drafting and feel very compfortable with that method. Another handy tool is to take photos of the area in question, blow them up to a workable size and then do tissue paper overlays sketching in the appropriate plants at the appropriate sizes. That combined with a layout to scale on graph paper should get you a long way.

There are also various DIY landscaping texts that would be helpful. Sunset's Western Landscaping, the companion to the Western Garden Book, is pretty good. My library is still packed or I'd suggest others but Lowe's and HD usually have a decent selection in their book/magazine area. Look through and find one that presents a reasonable discussion of design principles and a step by step method to preparing a design. That should help a LOT!