Cool! I'm really looking forward to seeing your floors once they're done!
Initially we wanted to use reclaimed pine (12" planks) but upon closer inspection most of them were too far gone to reuse as a complete floor - well worn, big chunks missing from where some moron installed an oak herringbone floor on top using ring shank nails and some just plain bad right from the beginning, chipping off along the growth rings (I used to know the proper term for that kind of behavior, but I forgot it). So in the end we decided to buy new flooring for the back bedroom and possibly the kitchen (unless we stumble across a large amount of decent salvage flooring) and use the old pine for the living room.
The living room is quite a mix - we could save some of the old 12" pine planks which were mostly wet-rotted from below, then we have some salvaged pine subfloor planks and if that isn't enough we'll use the leftover salvaged pine.
For the hallway (which will get most traffic) we used salvaged oak T&G, 3 and 3 1/2" wide. Apparently it came from several different rooms, some of which fared considerably better than others. The worst ones have plenty of chunky screws in them because someone laid down luan and roll vinyl on top.
That's the worst of the oak:
That's how far I got installing the floor... and I might even have to take it up again because the sleepers are too high, higher than the door frames.
The tongues and grooves don't quite fit, so there are some small gaps, but we can live with that. I hope to get it installed during the Easter holidays, but I have no idea when we might get around to sanding and oiling.
BTW, the white stuff is perlite. The floor is concrete slab, then some kind of felt they typically use in road construction, heavy plastic, small blocks of wood and sheets of cork for leveling and sleepers on top (dimensional 2x3).