Save this wood?

We need to decide whether or not to save and reuse the old wood that we're tearing out of the building. We've been thinking about using them as flooring. We've got three kinds of it: old 2x4s that were used to frame the rooms, ceiling joists that are holding up the roof, and roof decking that's laid on top of the ceiling joists, covered with a layer of tar and gravel and then topped with the roof's rubber membrane.

Yesterday our contractor met me at the RBB with his portable planer and a Sawzall. He cut out pieces of each and cleaned them up. Then I brought them home for us to consider when the bf got home from work. This is what they look like:



From left to right, it's: decking, joist, framing 2x4s. We think the decking and joists are pine and that the 2x4s might be poplar or hemlock. If we used them for flooring, we'd lay the decking and joist wood as (fairly wide) planks and the two by fours in a herringbone pattern. The plan is to buy some stains and urethane, apply them and see what we get. Then maybe take our wood bits to an antique wood flooring place and compare them to what we could buy off the shelf.

If we don't use it for flooring, my bf had the idea of using the joists (which are much thicker) for our new staircases. I like that idea. I also like the idea of saving some of the wood to make furniture for our new place or maybe built-in shelves.

You may be wondering why we'd even consider having the demo crew just throw the wood out. Answer: it's probably more expensive (and possibly significantly more) to dismantle everything carefully, pull all the nails, cut the planks to the right lengths, plane the layer of tar off the roof decking and then plane all the pieces, than it would be just to buy ready-milled flooring. And since we need so many square feet of flooring (about 3000 sq. ft of wood, plus tile for the bathrooms), the difference between, say, $10/sq ft and, say, $15/sq ft is gonna add up fast. So we really do need to cost it out.