Old growth,straight grained Doug Fir is still used in the manufacture of Fireman's Ladders and often used for spars in our area. I've attached a website here of someone in Homer with some very old Doug Fir spars for sale that points to their longevity.
http://www.wealaskans.com/mast.html
There is also a mill in NW that advertises they have
High grade mast and spar stock available. They're website is http://www.timberwork.com/lumber.html