You can get an engineered floor that is as good if not better than a solid product. We produce solid unfinished flooring but we also produce unfinished engineered flooring as well. Solid flooring typically has a 1/4" (6mm) of "sandable" or "usable" surface. Basically after you get 1/4" deep you'll hit the nail heads and so you can't sand below that point. Our engineered unfinished product has a 5mm wear layer. However, the engineered product is already pre-sanded to 80g which means once installed the amount of sanding that takes place is minimal. On a solid floor, most contractors will need to do a rough sanding to get the floor even, then one or two more cuts to get it smooth. Even if you have a very talented sander he is going to take 1/32 off in his sanding on the solid floor. That equates to roughly 3/100 which is nearly the difference between the 6mm and 5mm usable surfaces we began with. So in essence, you are getting very close to the same "usable" surface. Not to mention the engineered is more stable, will keep you from having to install a subfloor as it can be glued directly to concrete, eliminates transition issues between hardwood and tile or carpet AND should take less time to install. My two cents. Sam @ Real Wood Floors realwoodfloors.com

Sorry, I completely misunderstood your post. I thought you meant a transition piece between the two floors (ie, schluter, t strip molding). Don't grout that joint between the two floors. It needs to be caulked if you go that route. Otherwise, the difference in expansion/contraction between the two materials will cause the grout to crack. As far as grout color, look at lots of pictures. I would think you'd lose a lot of the beautiful herringbone pattern if you tried to match the dominant color. The tones of the two floors are very similar, so they already connect on that level. I don't think you have an issue of transitioning in terms of grout color. I guess the more natural selection for a wood look would be a little darker than the main color, like a shadow between the boards. A lighter color or a gray will look more like a tile floor with grout. I wouldn't do something lighter, as in peachy. You can kind of see what it would look like lighter right now. The higher the contrast you have with the tile will affect how busy or pronounced the floor pattern will look. Maybe you could cut strips of colored construction paper to lay over the joints to see what appeals to you more. You've got some variation in the tile colors, but when you use a grout color that matches the flooring, the floor becomes one big solid mass of color. Here is a link that might be useful: herringbone tile pictures This post was edited by snookums2 on Thu, Aug 8, 13 at 23:15

Hmmmmm, a flooring PROFESSIONAL who thought a floating hardwood floor would be "click and go". Oh dear. This person is NOT a flooring installer. A PROFESSIONAL flooring installer (not a General Contractor) would know that 99% of "floating hardwood" floors are NOT click-together. And living in the same neighborhood does not mean he would "know" the concrete wasn't level. Did you PAY for concrete leveling??? If you did, now MUCH did you pay? And are there any OTHER areas where the floor bounces? If there are, you have a floor that was improperly installed....because part of proper installation technique INCLUDES a FLAT AND LEVEL subfloor. And why was the mirror left IN PLACE??? If this is a $200K renovation, why would a contractor leave a mirror door in place? I'm going to tell you the cheapest solution: remove the mirrors, reinstall the hardwood PROPERLY (with leveling) and then reinstall the doors or BUY NEW ONES that fit or can be trimmed to fit the space. I have a feeling there are other issues with this renovation....but I don't know if you want to open that can of worms.

+1. There is not way to have a zero gap butt joint there. Caulking, assuming he tapes off to the hardwood/threshold and doesn't get any on those surfaces, it appropriate here. You can also cover the transition with a piece of shoe molding if you prefer.