Gil,
I offer all three woods in tapered shafts, Hildebrand Spruce, POC, and Surewood Fir. The spruce shafts may be my personal favorite, but they are a bit lighter than cedar in general, with Fir being the heaviest of the three. Douglas Fir is an excellent wood that's strong, stays straight (given the right finish), and is heavy. I like the Spruce because it has the highest strength to weight ratio, and is very easy to straighten to precision specs.
However, I have been experimenting with methods of adding significant weight to the lighter woods, and have been having great success "pressurizing" finish into the shafts. I have some cedar shafts going through this process right now that started out as 430 grain bareshafts and are now up to 640-650, and I'm going to topcoat over them. I think this would be perfect for someone who wanted to shoot a heavy spruce arrow.
Craig