If you want to get serious about designs and you have the construction knowledge and creativity, then why not give dynascape a look. The amount of time you'll save with hand drawing and coloring will far outweigh the initial cost of the program. Here is a design that was put together in an afternoon. I was also able to take measurements and quantities of materials with a click of the mouse as well, something you can't do with hand drawings.
Btw your second design is much better.