I'm 5' 11" (roughly) with a 32in cycling inseam and I prefer a 55-56cm "square" (equal seat/top tubes) frame. I usually end up with a little more than fistfull of seatpost and between an inch or two of saddle-bar drop. Fine by me, even on my commuter.
Ride what's comfortable. KOPS (knee over pedal spindle) is a good way to start (though far from law), then adjust your bar height to suit your comfort.
-Gene-