My first pair was probably something similar to the Shimano MT-40's (multi-purpose shoes). I liked them (they definitely keep your feet warmer in cold, etc.) and they look more like regular shoes, but after riding for a few months I wanted Sidi's. The cloth shoes tend to get pretty beat up by the cranks (mine did anyway), and even at less than a year old, the soles are kind of coming apart on the bottom.
Got Sidi's about 3 weeks ago and love them. Granted, they're not super comfy to walk in, but I still do it when necessary. Haven't had too much pain afterward, not more than with the Shimano's anyway.
So, definitely have her think about longevity and everything also. She may want a pair that look like tennies (the Oakley shoes are pretty good for this), but she may also change her mind in a month and decide that she would have liked something more functional. Not that the tennis-shoe like cycling shoes aren't functional, but sometimes the road-like shoes seem to be better to me.
Also make sure she tries them all on and gets a pair that fits (walk around in them, sit in them, maybe try to ride around outside the store, etc). I have a pair of Specialized shoes that are a few sizes too big. I wear them to commute to/from work instead of for anything else. Not really a good purchase.