Having just spent a lot of time trying to find the right cross bike, let me pass on a couple thoughts. In general bike fit is all about stand over height and top tube length.
I went to a local LBS and was measured for a bike. A system similar to, but a little more complex, than the system used by Zinn. http://www.zinncycles.com/newfitform4.aspx
. I took the "bike recommendations" and went shopping. I found myself "fitting" on several sizes, depending on brands. Gunnar, Redline, Bianchi, Ridley. Using the measurements I was "fitted" to a different "sized" bike in every case.
Ended up going for Gunnar steel! Fits Perfect.
Either use the Zinn link for measurements or get measured. I wish I had done so long ago and eliminated a lot of the guess work I have been suffering through.