I would not put anything opposite the collage you have now because your hallway is too narrow. Some people like to move as far away as possible from such displays to take the pictures in as a group. That wouldn't be possible in your space if you had stuff on the opposite wall--- they might back up to see one wall and knock things off the other one. In general, if you have a hallway width less than four feet wide you don't want to line both walls with anything. If you have a long hallway or one punctuated by doors, you can put a grouping on one side, then hang things on the other side of the hall, not opposite but further down, iykwim. I would use a nice painting or print at the end of the hall, unless there is something you want to reflect from the other end.

WOW Caroline. Lot of future plans. It looks like you have to go through the kitchen from master to get to bathroom? Or am I missing a door some where? HA I like the Aircraft house name too. I sympathize with you on the long narrow living room. I had one that was 26 foot long and less than 12 foot wide as I remember. I had to do it in two areas and even one time I had the dinning room table at the end and it was far from the kitchen but was a lovely view of the river and pool. And we only sat there when we had company. Master bedroom was the same long narrow room because it had been two rooms opened up. I think this is why I love my house and really want to stay here. I think I actually over estimated the SQ FT of it. Removing the three 6 inch thick walls it actually measures 1275 inside and I did not remove the other interior walls. Just out side walls and main wall down the center. It is a great size for one and even when both of us were here it was a good size. Just not as large as I thought. I was counting the total outside measurement. If I had it to do over I might change a coupe of things but it is good as it is. Still not sure if I will enclose half of the front porch. Since I moved my porch furniture to the nice cool shady carport I do not really have reason to enclose the front and I have enough space in the house for me for sure now.

The important thing is to make sure that you won't have too thin a sliver at the edges. Centering a board won't look appreciably different from not centering one unless the boards have obtrusive gaps between them. So put 3 or 4 boards tight up against each other and measure the width and divide by the # of boards. This gives you the average board width including the gap. Measure the hallway and divide by your average board width. Take the modulus and divide by 2. That's the width of the outer boards if you centre the middle board. If it's less than about an inch, don't centre the board. Similar calculations can be done for starting with a full board on one side. If the last board in will be too thin, then you shouldn't start with a full board.

What I meant was, bring thr upstairs fixture downstairs, move the downstairs upstairs and place the downstairs fixture closer to the front door, rather than in the middle of the hallway and add another fixture toward the end of the downstairs hall or augment the fixture with recessed lights.