http://www.pinterest.com/pin/210754457533698010/ If the columns are landing in the middle of that bare spot, it makes sense to highlight it with flooring running between the columns. Use boards as close as possible to the original floor width and have them flush with the old floor. Stain as close as possible to the existing colors and the difference in grain direction will make it blend in. Feathering in flooring across that spot is possible - IF you have matching flooring and can remove boards in an erratic pattern.

You need to do a little more archeological digging still. You need to know the whole construction of the floor before you can decide how best to install something new. I'd take up that plywood piece in the kitchen and see what's under it. It's higher than the surrounding floor, so needs to go. You should also be able to see from there what subfloor is under the original kitchen hardwood. It's too bad the space under your entryway is finished, but I'd still do some exploring from below to see what's under there, and to figure out the fix to stop it from squeaking. Is it drywall below or a drop ceiling? I know it probably seems like a pain to tear out drywall, but if you cut out a clean patch, like 2' x the width of the joists, it'll be relatively simple to repair. Just make sure to cut it down the center of the joists so that there's room to screw the patch piece to it later. Cut the hole under the area that squeaks the most, if you can. Have someone walk on and watch the floor from below to see what's moving. It might be as simple as pounding in a couple shims from below, or face-nailing a loose board from above. You want to find out what's underneath the hardwood. It might be laid directly on the floor joists, or there might be 10" wide boards that the hardwood is nailed to. Another thought is to take out a board in the hallway, since that's not original and you want to replace it. See what the subfloor is there. I am a bit puzzled at why, when you've stripped the kitchen down to the original hardwood, it's still higher than the hallway floor. Is your current surface perhaps not the original kitchen hardwood? Peeling back the plywood area will help determine that. BTW, I haven't heard of that stop squeaking product you linked to, so can't offer any personal opinion. And don't pour self-leveling compound over top of hardwood. It needs to go over plywood.

Thanks for the input! It is somewhat of a subfloor, but there is one more layer beneath this wood and the joists under the house. We can't put another wood on top, because it is already sitting higher than the oak in the dining room, so there would still be a threshold needed. And we really don't want any type of linoleum back in the kitchen. We went ahead and stained the wood this weekend, and it already looks fantastic. If we didn't have the oak right against it, we would have kept it natural with just a gloss coat to bring out the red and the old plank character. But we thought two natural woods might clash, so we went with a dark Jacobean stain. Will post a pic soon, once we get the threshold done, and everything looking clean. Thanks again! It's always nice to have second opinions

When it comes to hardwood, trends are something to ignore! Why? Because hardwood is pretty much a lifetime purchase, and unless yours is damaged in some way, you're probably not going to replace it. So, light wood vs. dark wood, wide planks vs. narrow planks -- that stuff's all going to come and go. With that in mind -- as well as the very real concerns about cleaning dark wood -- I'll vote for a nice, neutral midtone every time. Not too much contrast, not too red, and (unless it's a beach house) not too pale. I think this is the wood that's most likely to give you good service and stand the test of time.