My new flooring is done*. :D I replaced the old oak color with dark brown/black (TrafficMaster Allure Ironwood). In the dining room, living room, and entryway, I installed the new flooring in the opposite direction as the old (east-west instead of north-south).
I think this direction looks better. The difference is especially apparent in the entryway.
In the hallway, installation was challenging. I had to work around six doors, and the new flooring had to transition to existing flooring in five rooms.
Four of those transitions were in the center of doorways across from each other. There was no margin for error because even a tiny space between the planks would be obvious. It was a real victory to get them all matched up exactly right. :D
The transition point between bedrooms and hallway is clear. On the left, my bedroom still has the old oak color flooring. On the right, the other bedroom has walnut. In the middle is the hallway with the new brown/black flooring.
The transition between bathroom, hallway, and workroom is visually seamless because all three have the same color flooring.
The fifth transition is with the laundry room (closet, actually). Alas, it did not match up perfectly. I think the flooring in the closet shifted slightly when the old washer and dryer were moved out and the new ones moved in. But the gap is small, and it's only visible when the closet door is open.
*Done except for the kitchen. I am trying to decide if I want to replace the cabinets along with the flooring.