Geez...you know we can't answer this for you.

I would think that you really need her inseam measurement.

My first thought...and I'm a COMPLETE amateur...is that the 57cm is too small for her.

Is there any way that the bike shop could swap out the bike after she receives it in order to get the best fit?

I don't ride a WSD...I ride a regular Trek a 58cm. I'm 5'8" with a 34.5 inch inseam. Most people of my height do not ride a bike this big.

Have you considered the 5000 (not WSD)?

I personally would go with the carbon frame. And if this is an 07 bike it would be more likely that the bike shop would swap it out after fitting her.

just some thoughts