The issue with putting 2 different whites next to each other is that a lot of times you'll see people get it wrong. I suppose since your SIL has the color combo you are thinking about, at least you know it will work - at least, it works in HER house. Not sure if a warm white will look ok next to Extra White ceiling. Also, a lot depends on the rest of the stuff you pick, as floor color etc. can all have an effect.

FWIW, we did drift of mist in our house, which is really close to city loft. (City loft has more pink, drift of mist has more green, but side by side they look almost the same). DH thought it was still the drywall the first time he saw it (we get a lot of sun in our house - south facing - so the walls look very light). It definitely has color, but it's not enough to make it LOOK like color, if you get what I'm saying. I would put it as a variation of white, more than I would say it's a greige, but I suppose technically it's greige. Here it is in our bathroom with no lights on (so it looks darker than normal), and not completely done (ceilings had just been sprayed). Our trim & ceilings are SW Pure White.

In the kitchen, we did stained cabinet lowers and pure white uppers. However, we chose a darker stain so this might not be helpful for you if you're going light. Whatever you pick for a trim would be the white I would choose for cabinets, and I'd probably agree with your designer to use Extra White if it's the ceiling color. Cloudy day in the below photo. Mission oak stain on cabs.

@anj_p are your cabinets pure white?

They look a lot different then ceiling.

i havent decided if we are doing a lighter stain for cabinets or something close to yours.

I am concerned with city loft looking pink or dirty especially in living room that gets both south and north light.

Is extra white on ceiling really cool color? now it just looks like a standard white

@Zory ceilings are in flat paint, cabs are enamel, so that's part of it. The other part is that color looks different on horizontal and vertical surfaces. AND color looks different in photos than it does in person (my carpet looks pink-tinged in photos but has zero pink in person, my walls and cabinets look a lot lighter in person than they do in photos, etc.). AND it looks different in artificial light than in daylight. So take it all with a grain of salt.

I can't speak to city loft but drift of mist looks nice throughout our house. Our main rooms face south and east. We have bedroom and office spaces facing each direction. I had initially wanted white as well but DH wanted even darker (he wanted gossamer veil) so this was our compromise, and I'm really happy with it. Honestly I like the depth I get from a little more chroma as it makes the trim pop, so I'm kind of glad I didn't win.

Anyway, if you are building custom, I would think it would be OK for you to paint large samples so you could see what it looks like in your space. Or get the large samplize peel & sticks, and move them around in your house. I'd definitely take whatever color you were thinking and put it next to the ceiling to make sure it works.

@anj_p did you do drift of mist at full strength or lighten it?

I didn't lighten. Here's my built in right next to living room window. Cabs and shelves are pure white. Ship lap is pure white. Wall behind shelves and next to ship lap is drift of mist. You can see it looks lighter near the floor and darker near the ceiling... all due to light.

City Loft looks very pink in some lighting. I originally picked it for my new build but after seeing it in the house next door that was ahead of mine, I immediately changed it. I hated it! I just did extra white everywhere, I have tons of natural light so it just looks bright white. I am doing wallpaper in some areas to break it up (along with built ins, etc). It’s clean and easy for an open floor plan. Here are some photos in my build.

Meant to add it’s also on my ceiling.

I would agree with kr that if you really want white, I would match your ceiling and use extra white for your walls. The different sheen on trim will make it look different but you won't have any issue clashing. A lot of pros recommend that with white.

@K R is your trim also extra white and everything is in different sheens?

if i wanted white cabinets, also extra white? might be too much white…

I would get a designer to help w the colors! Mistakes are expensive and disappointing...IMHO if you're not pretty good with color and you have all that stuff to balance it would be a good investment.

Zory, everything is extra white (trim, etc) and everything is in flat. Easier. I may have the walls repainted eggshell down the road, but our kids are grown and our dog is tiny so flat should be fine for us.