Just for reference, I am almost exactly the same height as you and have a 30" inseam (crotch to floor). My road bike is a 48cm (it's a Cannondale, which I'm told runs big, so I'd likely be on a 49-51 in another brand). That translates to a 44 or so in a CX bike, since they have taller clearance because of the beefier tires. I'm suspicious that most of those bikes wouldn't offer you much, if any, standover. I'm currently looking at CX bikes in the 44cm range and even a Ridley in a 41 (their sizing is kinda weird and they have a big jump from their smallest to next smallest size).