I'm not bill_v, but we are using Laticrete Silver Shadow based on his recommendations several times in other people's posts on this forum. It is pretty similar to Mapei Warm Gray, I think, but I didn't compare them side by side. I know Bill has a few posts with example pictures of the Silver Shadow that you might be able to use as a guide.

Thanks, albryant! I'll do a search for silver shadow, I may even have that sample. I'm thinking a light gray, but not bluish. I don't want to lock in on a specific color, because I may end up repainting the wall color, and it needs to match.

Laticrete's Silver Shadow will give you the light grey, while the Custom Antique White will be more of a beige off white, taking you in an entire different direction, tone-wise. Either one would work well, depending on which direction you want to go.

thanks. did the custom brand antique white on sample board, and it is beigish. ever used warm gray by custom brand from hd? what is your thought on that color?