Our Powder Room is blue vinyl wall covering. Perhaps not the hue you are seeking. I had paint mixed to match at SW and applied first just to make certain no seam peaking caused a problem. If you like the color I can get the formula off of the label.

Here is a link that might be useful: Powder Room

I'm thinking BM Tranquility or Feather Gray.

Also, the following come to mind, you can go to myperfectcolor.com and insert a name into the search box to see a swatch (you can also order samples for next to nothing). All Benjamin Moore:

Iced Cube Silver, Harbor Haze, Patriotic White (v. pale blue), Beacon Gray (lite blue with some grey), Bunny Gray, Light Pewter (pretty soft powder gray), Revere Pewter (beige-y), Marilyn's Dress (soft pale gray).