Neutral grey shiplap walls
Let's begin with the spelling. Both gray and grey are correct. I find myself in the minority, using the "e" all the time. After (easily) 5 years, it's still the "new" hands down favorite for a neutral home. Gray has nudged beige, cream and off-white aside, only lagging behind white as the "go - to" neutral for residential interiors. Depending on who you are; your taste, your sensibility, the style of your decor, you either love it or hate it. Deemed cold and blah by some, it is considered a very sophisticated choice by others. It will create a calm and neutral palette for your home.
Some things to keep in mind to use it effectively: If you choose a very neutral grey whose make up is purely black and white, there is little complexity to the color (not necessarily bad) and this allows you to decorate with either warm or cool tones around it. Most greys however are either warm or cool themselves with visible undertones which lean towards blue, green, violet, red or yellow.
Each lends a VERY different feel to the room. Use the undertones to help decorate the room and tie one room's color to the next. There are many more than fifty shades of grey out there. Benjamin Moore say they have hundreds, Sherwin Williams has a lovely selection. C2 has some great full spectrum choices and Farrow & Ball excels at grey as they do with each and every other hue.
The biggest mistake is to create a room ALL grey. No matter how beautiful the color, it will bore the heck out of you in short order. The human eye, brain (and soul!) needs variety and the inclusion of color to make a room feel visually ergonomic and to keep it from becoming sterile. While it may look great in a photo, I promise you, living in an all grey room is too dull. Here are some good ones.
Neutral grey dining area
Warm grey distressed wall
warm grey kitchen
Warm grey dining room
Warm grey foyer
Cool grey dining room
Light neutral grey living room
Dont' do this!
This grey room is sterile
And Don't do this!
This room needs much more color to bring it alive and make it relatable.
How NOT to use grey. This room needs more variety in color.