Cheap hardwood floors in the concept room

I found some really affordable hardwood flooring at a local lumber yard. In fact, these 1x6 yellow poplar tongue and groove planks are so cheap, I can't really see how they afford to make them, but that's not my problem. Whereas most of the wood in our house (and all of the timber frame) is from our farm and cut on my sawmill, I am becoming very rational about trying to finish this house. When I can buy something for cheaper and better than what I can make it, then I'll buy it. The flooring is 50 cents a linear foot, which works out to be a little over $1/square foot (the 6" boards actually only cover 5.2" in width). What's even better, these are random length, with the average length being 12 feet!!!

As in these pictures, much of my house will have no plywood subfloor. Instead I plan to install hardwood flooring directly to oak 3x3's that were cut on my sawmill. The advantage of this is that I'll save about $2000 in not buying plywood, and reduce the amount of resins and glues in my house. (I'll take solid wood over plywood any day, because among other things, plywood burns so much more readily) The drawback to this flooring is that it is (yellow) poplar, not oak, which means it is not as hard. My wife and I rationalized using it in low traffic areas (kids bedrooms and closets), and resolved that if it doesn't work out, we can floor over this flooring in a few years and it will become the subfloor! (per foot, the hardwood floors are only about 40% more than 3/4 plywood itself!)

The pictures shown here are of back-to-back walkin closets that connect my two sons' rooms. We call this large closet our "concept room" because we're trying out our floor and ceiling concepts in the closet to see if we like them. If we don't like the finished result, well, it's a closet and no one will care too much. So far, we like the result - it looks like poplar floors are a go!