I found a really nice PLAIN white button down at Eddie Bauer. Its "wrinkle resistant" and the fit is nice... The one I got has a nice texture so even though I bought it as a layering piece, it is not as sheer as most white shirts I have tried so I could wear it on its own.
I have tried MANY white shirts the past couple months and there was always something wierd about most of them...the color was too high or stiff, the sleeves too long or too tight, snug across the back or too baggy. I have ordered and returned no fewer than 3 the past couple months. I was pretty pleased when I found this one...nicely fitted with no tight areas and the sleeves are actually the right length. And the price was not too bad either.
I am actually surprised how hard it is to find a nice fitting white button down!