We used 1x12 white pine planks, surface nailed with cut nails, in our log house. It is soft and I would recommend putting pads under the heavier furniture (including chairs) so you don't get the dents. Also don't use a varnish finish (especially polyurethane), it is hard to repair. We used a floor oil that you could just wipe on an area to restore the look. Otherwise we really like the subtle wear you get on it, perfect for the log house.
If I had to do it again I would not be so quick to put it down but would let it dry very well and run it through a surface planer so it was very flat. I've also heard of cutting and placing it down loose to get some wear on it, then taking it up and finishing it and nailing down with tight joints. Depends on how primitive you want it to look.