From what I hear, practically everyone hates elves. Understandable, I suppose. But one of the biggest things is how they might sell something made of wood to you... then later you try and offer it back, and they get all offended! I think this can be solved simply by introducing magic, enchanted, or whatever-fancy-whatchamacallit-worked wood.
Basically, for every type of wood out there, there is a "magic" version of it that the elves created. It's pretty much exactly the same in every respect except you could say it has a little stamp of approval by the elves, guaranteeing that no plant or animal was brutally slaughtered in its creation. Whenever elves come to sell you blocks of wood or items crafted from wood, it will always be the "magic" variety. Thus if you were to craft something out of that magic wood and sell it back, they would not be offended because they know the wood was magically created.
It may even be interesting to hire an elf to work with some trees and magically extract wood from them. You'd just have another unit added to your fortress that is an elf that I suppose could do most things other dwarves could, except this particular unit could be given a task targeting a tree called "magically extract wood". Though I suppose that would be really slow and not worth it to many players who already hate elves so much!
Also, looking at this idea...
http://www.bay12forums.com/smf/index.php?topic=19567.msg203770#msg203770It isn't so bad, but I think such wood would be of low quality.
Edit:
Other possible descriptors we could give the wood are "Blessed" or "Spirit".
Also, we should consider if maybe this type of wood is in fact stronger than mundane wood or if it adds more to quality and enjoyability (especially for elves).