C.C.
I'm big on top but normal in the waist and hips. White House Black Market works well for me. I am a 36DD, and I'm 6' tall and a size 10, if that helps.
If you are smaller (shorter), how about http://www.bostonproper.com/ ? They are forever sending me catalogs, and most of the models seem to have a good amount of cleavage. My only issue with it is that their pants are nowhere near long enough for me (I need a 36" inseam at a minimum). I love their stuff, though. Super cute.