At 5'11" with 33" inseam, I can ride and have ridden anything from 54cm to 60cm. But 56-58 feels about right.
My two road bikes are old school diamond frames: '89 Ironman with 57 or 58cm frame; '93 Trek 5900 with 56cm frame. The Trek is carbon but built like an old school diamond frame, not a compact. I'm not even sure it's a true monocoque. Looks like one but I'm not sure what's under the skin. Anyway it rides like my Ironman, just lighter in weight, which is nice on climbs.
But after getting the Trek 5900 early this year from a friend, it's taken more effort to dial in the fit. That's partly due to some neck and shoulder pain from old injuries. I've swapped saddles, handlebars and, finally, stems, in and out for months. Finally settled on a combo that seems right.
But I couldn't seem to get the saddle height dialed in. I finally used the Ironman (very comfy fit) as a reference point, measured everything, and transferred the adjustments to the Trek. There's still some guesswork since both bikes have similar but different saddles, bars and stems. And the Ironman has downtube shifters and old style aero brake hoods, while the Trek has brifters which elongate the reach by at least an inch. The Ironman saddle is scootched forward a bit on the rails; the Trek is scootched backward about that same amount -- not to accommodate reach, but for knee comfort and pedaling efficiency. Seems better now, though. I'll see this week after a couple of group rides.
Overall the 56-58cm range seems about right for me. But with almost any road bike I'd need to swap stems to something shorter to suit my needs for neck and shoulder comfort.