So....the only room on the first floor with hardwood right now is the den? You can put hardwood throughout and refinish the den in the process, everything will match downstairs and you can get it close enough no one will notice if it's slightly different on a different floor. No to engineered flooring if you want to try this. Why is someone suggesting oak of a different plank width than what you currently have? Odd. golden oak finish is pretty neutral. better to have the whole house match than to have one level trendy and one level classic.

functionally it sounds like the materials were well chosen- carpet for a play room, tile for an entry and powder room...could be just a personal design choice. Pictures would help.

Install new sand on site select red oak for all tile and carpet areas, slightly change board width if you like, and completely RE FINISH the existing flooring at the same time. It may be not the most perfect match, but they will continue to blend over time. Do not introduce new flooring of a far different tone or species . Just don't do it.

It is possible your floors are natural red oak rather than "golden oak" because the oil based finishes used on wood floors amber over time. The flooring itself is not dated though the finish has aged. That flooring has been used in homes for over a hundred years and is in many elegant homes. Unlike other newer styles of wood flooring, oak is not discontinued and can be found to match or repair floors. It is more timeless than trendy.

If you do not like the red undertones in red oak, it can be lightly stained by a skilled floor installer with a stain that will reduce the red tones and bring out the brown.

Thank you all for the great comments.The existing oak hardwoods are not only in the den downstairs. They are also in the entry foyer, the dining room, living room and gurest room. One half of downstairs is the oak, the other half is the tile and 1 room carpet. The finish on the oak could be a little different on the floors, the finish info is what the floor made said.

oops. the finish on the oak is what the floor man said.

That's also a good idea to wait. We are in the remodeling process and we may want to enjoy living in the updated look, but who knows, maybe we should wait.