Guys with real jobs use these every day and they've been an advertising tool to those who sell to the working man for decades, but I love having these in my toolbox as a great drawing tool.
I'm always on the lookout for vintage advertising pencils; they're a real throw back to the good old hardware store days. The ones above are not so vintage (except for our sadly lost New Dorp Lumber). These are usually quite inexpensive so they're easy to stock up on. (Home Depot and General's are made in the USA!)
You can get a wide range of marks with this simple tool. The only drawback is it might feel a little awkward to hold the square barrel. My solution was to squeeze a jelly pencil grip around the end. I also use rubber hair scrunchies; they go on much easier and you can adjust them quickly.
I'm not alone in my love for carpenter pencils, but the bane of using them was always sharpening them correctly. The two smaller sharpeners above sharpen to a point. They're quick, but you loose the full chiseled point.
I found this handy item at Pencils.com. It's a two step sharpener that makes short work of the big shavings and keeps the flat graphite in tact. Afterwards, I use a razor knife to trim it down to the point that I want.