So after looking at way too many whites for trim, I finally decided on what color to go with what I'd call a 'dark white' wall color that we'll have throughout the house - Benjamin Moore's 'Deep in Thought'.

I went with a 25% tint (which they sometimes confirm as 'so minus 75% of the color?') of Deep In Thought for our ceiling paint (they mixed it with Base 1).

That looks a hair too light for my taste for door trims and cabinets (but someone might like it), so I'm going to get a 50% tint for that.

Just wanted to say after seeing other trim whites and noticing so many of them cast odd colors or looked too white or too this or that... I'm loving the idea of going with the % mixes. And would recommend this approach to anyone messing around with whites and off-whites for wall color (or even just trim and cabinet color).