I would do it white. Maybe BM White Dove or Chantilly Lace

Same here, white.

I was hoping for a little contrast between the trim and walls though. My trim is currently atrium white but eventually will be painted SW pure white like the rest of the house.

"but eventually will be painted SW pure white like the rest of the house".

No to "eventually" Paint the trim, which is too yellow for the look you want. It's the reason you wall color looks "blue",

Or just paint the walls atrium, and flat finish, to contrasr with trim finish. Until a bigger change. A yellowed trim never works well with blue OR gray walls: )

Sw pure white is “ too yellow? My wall color currently is Wickham grey which looks Very blue in that East facing foyer. I loved the blue cast prior to redoing my kitchen and DR, but now it screams blue.

Atrium!!!!! s too yellow. Trim needs the pure white, otherwise, match the foyer walls to existing trim ( atrium ) .........until you change to match the rest.

Atrium has a pink cast, not yellow to my eye at least. The wall color is bothering me more than anything right now. My painter is coming next week to paint BM classic grey. The foyer extends all the up the stairwell so its a big job. Next step is the trim, then new runner.
Any runner suggestions given my view of DR ( pictured above)?

Here’s a pic of the Wickham grey in foyer / hall next to my kitchen with all SW pure white paint on the trim.. Sure still looks blue to me!! So it’s not the “ yellow atrium” making the walls look blue.

Trust me- Easter egg robin blue. Btw, the baseboard molding seen is Atrium white while the kitchen doorway molding is SW pure white-not much of a difference

I’ve already done that- that’s how I narrowed down my choices😉

Well, go with your gut and take a leap. It's never easy.

I seem to remember some agony over a paper /wainscoting thing in dining room? The mirror is not helping the new paper if I am right on that? A narrow "tease. and too small : ) . Art? Even better there. or a series of three related prints. .

PS I'd try Edgecomb Ben Moore : ) Works great in 1/2 strength formula too.

Yes! Some folks on that thread were insisting that the wallpaper I chose looked great in the book because it was pictured with “ glazed wainscoting “. Nothing I could say would convince them otherwise ( that it was just shadowing). Im very happy with my Pure white unglazed wainscoting and love it with the paper although ......it can appear to have a light grey cast at times depending on the time of day. You’re not alone thinking the rectangular mirror is too dinky. It’s not moving though, I adore it !! A row of pics are going on the opposite wall.
I’ll check out the 1/2 str Edgecomb- greys are such a challenge!