Bumping this up

@Stephanie Sanborn I don't know if this will work with only one paint coat. I suggest you try it in on a large board before going to the expense of the walls. I took your original Light Pewter and minimized the Chroma, making the suggestions more grey. HueFamily/Value(lightness)/Chroma(colorfulness)

BM 1471 Shoreline sits very close to your original color but is more greyed. This area of the color wheel unfortunately can be tricky as unbalanced light, may make low chroma colors look a little violet. You may not mind, but some people do. BM CSP-500 Whisper is moving away from this tricky zone, so may be more what you are hoping for. It is still in the same Value as Light Pewter, but greyer and may not show purple in unbalanced light. It's my safer pick. All that said, you need to test them.