You can make the color change anywhere you want. In old houses I have seen, the first-floor flooring was carried up to the first landing (if it had one) or to the top of the stairs if it was a straight staircase. Then the lesser flooring took over. The objective was to make it look like the expensive stuff went all the way up. One house had three changes of flooring: something hardwood (walnut or cherry) on the first floor, which went up to where the staircase turned, then oak for the next floor where the main bedrooms were, then pine or cypress going up to the nursery and attics. The servant's staircase was pine all the way. The only house that had fancy all the way up also had a ballroom on the top floor ... can't have the guests stepping on pine!

The stairs *should match the "public" area flooring (as in the main living area floors). If the upstairs is for bedrooms and games room, this would be considered "private" (for the homeowners). If the main floor is the "public" area (living room, kitchen, dining, etc) then the stairs going UP should match the main floor flooring. The reason: the stairs are visible to the public and therefore they should match the public area floors. Now for tiles in the upstairs area. This is not common but it has been done. It takes extra work (and extra materials = extra money) to get this to work over wood-joist construction. The subfloors will have to be assessed for deflection rating. I'll assume they rating isn't good enough for tile (tile is VERY HEAVY and requires very STIFF/thick subfloor). That means you'll need another layer of plywood over top. That plywood will change the height of the subfloor at the TOP of the stairs...which can mess up the stairs themselves (according to code). And then you have to add the tile which can often add as much as 3/4" height - which can again mess up the top step which messes up the stairs yet again. And then we get into the "tile is loud" concept. It is extremely loud. It transfers noise "up and down" (from upstairs to down stairs) as well as "wall to wall" (down hallways, into the bedrooms, etc). To deal with the noise and echo, you could be looking at changing the doors to solid core (expensive proposition depending on how many doors you have). And if you find the noise transfer TOO much (up to down) then you may have to rework the ceiling on the main floor (pull it down, stuff it with acoustic insulation, replace ceiling with acoustic drywall, etc). You can see the $$$$ signs flying out the window. Please look at the upstairs as a part of the whole home. Ask yourself how big your MAXIMUM budget is (once all the bills are paid = includes labor as well). And then find out if it can handle the "extras" such as new subfloor and possibly a stair case that has to be updated to allow for the extra height at the top of the stairs (rebuilding stairs is one of the most expensive projects in the building industry). Then make your decision as to whether or not tile on the second floor is a good idea FOR YOU. You are the only one who can answer that question.

I like the stairs to be the same as the main floor since that to me is what you see together form the main floor. But lots of people put a runner just on the stairs so I think do what you like.

Match the stairs to the walnut stairs in the main house. If you want grey on the lower level I would use a material that actually comes grey- slate for instance. Those grey fake wood floors scream fake since wood isn’t that color naturally.