Warning: (learning from just painting Grey in my living room that has loads of windows and light) Most Grey colors turn out much darker looking once you paint them on all the walls. We spent $2,000 to change the grey in our livingroom to a lighter grey because the first one turned out too dark and that was a grey that was much lighter than any you have choosen. I had even gotten a sample and painted one wall to test the color but when the walls all reflect off each other it gets way darker! I would test Beacon Grey or Breath of Fresh Air. We ended up using SW 7071 Grey Screen You can see in this photo how much darker it can get depending on the shadows and lighting. Here it is in the day light: During the day it is almost baby blue but at night it is VERY grey.

the back wall a redial brown brick with niches in between. the one wall has a narrow niche. I was thinking 2 or 3 colors. 1 light 2 dark. I am leaning towards a blue and green. maybe 3 is too many. flooring is dark which makes me feel light on walls. suggestions appreciated.

Smokey blue

You'll have to sample because you have beige and gray in the floor and it's difficult to tell from a picture on a monitor exactly what will work, but I suggest you look at BM Edgecomb Gray. SW Accessible Beige is close to EG. But I think you might be better off with a lighter color for a hallway, so look at BM Soft Chamois too. But while you say you're looking for a neutral I encourage you to look at blues or greens which would be more interesting - maybe in the treatment rooms.