Your statement is correct, SR, but your taxonomy is off; none of those softwoods are in the Pinaceae, and the different types of cypress, cedar, etc. are full species, not subspecies. When people use cypress and cedar in tanks, they usually are using baldcypress (Taxodium distichum) and eastern redcedar (Juniperus virginiana); other trees with similar names have very different woods (which may be unsuitable for tanks) and are in fact not closely related to those two species.
Sorry, I'm a geek. :grinyes:
More to the point- AC, if you can find a bone-like piece of driftwood that is already bleached gray and has all the bark worn away, that is ideal; this means that any potentially toxic resins have all ready leached out, and the more readily-decaying parts of the wood have already decayed.