Often the design is little more than a scribble... just enough to work out the specific ideas, fonts and textures I might use. Customers never see these roughs for they only serve to gather my thoughts - before I sit down in front of my computer.
Sometimes I do a little more work on these sketches. The font is nailed down, as is the background texture. Bevels and such are part of this rough plan as well. The idea is pretty much nailed in these more complex sketches.
And then there is the full blown concept drawings. I spend more time working out the ideas in my sketchbook, often as multiple drawings of various parts. Then I scan the sketches into my computer and using my drawing pad, rearrange and resize the components and then on a new layer redraw a final rendering. These drawings are for presentation to the customer. When it comes time for production I trace them again with vectors to start my routing files.