The recommendation to go into a shop for some basic bike fitting is good, and try out as many brands as they have to get a feeling for how they differ for height and reach (basically, top tube length, as most will have 100-110mm stems standard). Then, check out this calculator. Follow all the instructions...you might need help. Using a book between your legs for that measurement is helpful (you'll see what I mean when you do that measurements). Bike Fit Calculator | Find Your Bike Size | Competitive Cyclist

I was riding a 58cm 2011 Trek 2.1, which was always a little long for me but the right height. I had to run a relatively short stem...not ideal. When I switched to a 2013 2.1, geometry didn't improve much, but when I went hunting for a Trek Madone carbon frame I dropped to the 56cm and it was a great improvement, and necessary as the reach on the Madone carbon frames was a tad longer than their aluminum. On the other hand, if I were buying a Domane frame, I would definitely ride the 58cm size. FYI: I'm 6' tall, 33" cycling inseam (not the same as a pants measurement inseam, again, you'll see this on the measurement site above). When you go shopping for the right bike online/Craigslist, remember that stems are easy and relatively cheap to change, but you want to get a frame that is a reasonably good fit to begin with. With today's compact frames, you'll often fit (legs) perfectly fine on 2 different sizes from any manufacturer, but the top-tube length will determine how much you have to stretch out to the handlebars on that particular frame/size/manufacturer.