I find Pro Landscape to be a professional design tool capable of creating excellent CAD plans, including hardscape plans, and it also does a great job with 3D imaging, which is an excellent sales tool. With the addition of Techo-Bloc with this version and more hardscaping manufacturers n the works, Pro Landscape leads the way with imaging and hatch patterns for hardscaping designs.
There is a hardcape forum that many members use Google Sketchup and even have a member creating lessons to learn or use Sketchup. The most important thing with any software ir to relate a quality design and enable your client to understand the vision you have for their project. No software can do this alone, it is just a digital pencil or presentation tool.