I recently discovered Microsofts new cloud fonts that come with display-optimized variants. Of those, I particularly like Tenorite display for the calendar as it is a good deal narrower than Segoe UI variable display, which I continue to use in all grids, thanks to Pierre's recommendation.

Less pertinent to IQ, I love Google's Nina font for when I want to get a lot of text onto a page while keeping it pleasurably readable. I've found no others that compare.