I am 5'9" and I ride a 53cm Via Nirone Veloce with a 135 stem. I have a 53cm because my Infinito is a 53cm and I wanted a training bike with the same Geo so everything would be consistent between my rides and the Infinito has a 155mm headtube so I had to go with a 53cm (I should be on a 55cm but the headtube would be too high).

With that said, get a 55cm Via Nirone with a 120mm stem or a 57cm with a 100mm stem and you will be happy. Depending on your flexibility you might need the 55 to get low enough or you could be ok with a 57cm. Personally I feel like anything over a 55cm rides like a caddy so I would go with the smallest frame you can without going overboard.

Bianchi vs CAAD....no contest in my mind. CAAD make top level bikes but they are uninspiring clones when it comes to aesthetics....personally I think only specialized makes unique looking bikes out of the american manufacturers, but once again, welcome to the clone army. If you dont mind the cookie cutter look then CAAD is also a fantastic ride.

Forgive the crappy cell pic