My Client had wireframe plans and perspectives, but wanted to show a warmer atmosphere. I created all the equipment on the counters separately so they could be moved or changed, then combined them in Photoshop.
Once I get an idea, I often create a Google sketchUp model and play around with shapes and configurations, spurring more ideas. I might spend time in Adobe Photoshop to flesh things out. As you can see from the final artwork in last weeks post, the computer is just a framework for the final piece.