My gut instinct says that a 57cm will be too large for you. Hard to really say with today's convoluted geometry. One of my bikes (Trek Madone) is a 61cm frame and it fits me perfectly just as my other bike (Kestrel) which has a 59cm frame. Both have the same top tube length and seat post length. (I'm 6'3" with a 34" pants inseam)

You really have to be fitted by a bike shop. A first cut, if you have a friend willing to help out, is to run through the Competitive Cyclist on-line fit guide, (link in upper right corner of main web page, called "fit calculator".) It will take you about 10-15 minutes to run through it. Then, choose a bike based on the geometry specs and not what they say the frame size is. Most important number is the top tube length, secondarily is the seat tube length. And, the rule-of-thumb says that it is easier to "size up" a frame than to "size down" a frame. That means that if you get a frame one size too small, it can be made to fit you. If you get a frame one size too large, it will never fit you.

I really like the Bianchi bikes, (just purchased one for my lady friend, an Infinito). If you don't buy a Binachi in Celeste color ... well, then you don't really want a Bianchi and might as well get the Cannondale. I have been wanting to purchase a Bianchi Sempre frame, but there are no more in my size ... in Celeste. Availability of other colors, yeah, there are a few left, but they really aren't Bianchi if they are not Celeste.