realtime landscape architect,best program i have tried and use on a regular basis.
the program sells the jobs and get customers interested when looking at your adds with the pictures from it in there.
try it take some time to learn, online they have tuts to show you and you will be surprised with the stuff you can do, you can create custom models in sketch up then import them into the program. or you can even use already made sketchup designs others have done to put in the design to so the finished products, like unilock and other companies.
you can import a site plan and put the dimensions in and have a working site plan to design to. you can use the photo version to do what you asked above as well.