I went though 9 sample jars before I found the right taupy-gray for my new kitchen cabinets. Grays are hard -- they look SO different on your walls then they do on the little paint chip. Each one of the 9 I thought would be perfect when I bought it, but it would end up looking too blue, too green, or just brown (not taupy-gray).

I ended up picking BM Eagle Rock, and love it. But it's probably a bit to dark for walls (depending on where you are planning on using it).

You could try some these by Benjamin Moore: HC-172 Revere Pewter, 981 Winds Breath, 1474 Cape May Cobblestone, 1550 Cummulus Cloud, 1551 La Palaoma Gray. If you prefer Sherwin Wms, try some of these: SW7030 Anew Gray, SW7043 Worldly Gray, SW6072 Versatile Gray, SW0037 Morris Room Grey, or SW0054 Twilight Gray.
Make sure you look at these colors in different lights - sunny day, cloudy day, night etc. Colors will change, sometimes greatly, depending on the light in your room.