"I did find a website that indicates an 18" board will shrink about 2/10" from green to "kiln dry" across its width." If only it was that small. For Eastern White pine the tangential shrinkage is 6.1% wet to oven dry. This means a flat sawn board will move ~1.1 inch from completely wet to dry. A radial sawn board would move about 3/8 of an inch, but would have to come from a tree over three feet in diameter. The movement in a protected location will be less, but not zero. 0.2 inches sounds more like a seasonal movement for an 18 inch board, not wet to oven dry. The "Wood Engineering Handbook" linked above provides Table 3-4 to determine wood moisture contents as a function of RH and temperature. Equation 3-4 can then be used to determine shrinkage values. They are NOT small numbers for wide planks. The normal tongue and groove installation works well since it does allow for movement. Only one side of the board is fixed, and the other side is free to move as the tongue slides in and out of the groove. If you look at a lot of older wide plank floors you will see many with splits around the nails from the movement. The gaps also can be rather wide during heating season.

Would sanding the wood floors irritate your childrens' asthma? The fine dust you don't see is actually worse for your lungs than the bigger particles you do. We paid over $8/sf for reclaimed barn wood (pine) about 5 years ago in upstate NY. I'm not an expert on removing flooring, but what do you have to lose? Remove a few. The first few will be the hardest, then if you're careful, you might be able to get the rest up cleanly. My guess is that you'll have a % of damaged boards, but you might be able to save most. You can then salvage some of the damaged boards by cutting out the bad parts. We removed a T & G wood ceiling once and my husband did his usual UNcareful job. We still managed to salvage a lot of it. And on the floor you'd have more control. As for health concerns with old wood, I don't know. There might be lead paint traces on it. There was on our old barn wood. Maybe finishing the floor will seal everything in... I don't know. good luck!

Yes, pine splotches. The only variable is how much. Conditioner minimizes the blotching.

Thank you for the comment, @Sombreuil We have roughly 1600sqft of the floorboards, almost all of which are in good shape (we can see the underside of the floor above since we're down to the studs.) The homeowners of yesteryear actually put down newspaper when they covered the subflooring with layers and layers of linoleum, so they were largely protected in many places. We are hiring a company to pull a denail them- we are not planning on doing this ourselves! The flooring in the kitchen photo above is not really the target color- the cabinets, however, are the color we're hoping for in our kitchen. We are not really looking for a gray undertone, but certainly not a very yellow one. More so something with a bit more richness and a bit darker, which is why I was looking for suggestions from the fine folks here...