I would be hesistant to go with the shop owner's opinion based on height. His wife may not be as leggy or have a longer torso, etc...

I am 5'2" and am not built like every woman who is 5'2". The other guy said the 54 seemed too small, I would trust his opinion more because he was there! After having a Serotta fitter adjust my bike, I am convinced they know their stuff. Maybe the LBS has someone who has been to the Serotta class? As much as you want to support the LBS, don't let them talk you into a bike that doesn't fit. I wanted to support the shop I had been using for years and ended up with a half-a** fit. Ironically, this is the same guy who fit my first road bike perfectly. Okay, off the soap box.