Did you know they make 3.5 inch redwood fence posts. I was thrilled when I found that out. I used them for this project here: http://ana-white.com/2011/08/raised-raised-planter-bench and had some leftovers. I need good outdoor wood in my harsh climate and so made these with the leftovers.
I actually added 3 inches to the legs so I could have them tall enough to eat at my table with.