The good wood you and I remember from years ago was from big trees.
Those have mostly been cut down years ago, and the rest are in
protected areas so our grandkids will believe us when we tell them
that we had spruce and fir trees ten feet in diameter. Clear-cutting
practices leave us with a lot of small trees (the larger stuff is
either shipped to Japan or made into plywood), and small trees are
full of knots throughout their length, unlike the really tall ones
that had no branches in their lower reaches. Shoot, I've seen
two-by-fours that had bark on all four corners. We're getting
desperate.
In aircraft homebuilding, we buy wood from the aircraft suppliers.
It's really expensive, and getting worse all the time. Most builders
are switching to composite or aluminum. For boats, I have sought out
the smaller, friendly lumberyards (try the small towns) and those
fellas will often let you pick through the stuff to find better wood.
For my son's Squirt, we have found decent spruce and pine in
two-by-eights, since they have to come from larger trees, and we've
been able to rip them up to get the clear lengths we need. Some wooden
airplanes are still built this way.
There has been a "synthetic" wood developed that shows promise. By
cutting trees into long, slender slivers, like long toothpicks, and
laying them into moulds and adding waterproof binders, a clear, strong
(but a bit heavier) lumber is produced. I haven't seen it yet, but
there has been debate among aircraft homebuilders about trying it.
It's disadvantages are the weight, a tendency to fail suddenly when
overstressed, and the cost, although I imagine it would be much
cheaper than aircraft-grade spruce.

Dan