I would suggest the Palmer House for the kind of old-time hotel ambiance I think a 12-year old girl would like. Fancy high-ceiling lobby, uniformed doormen, etc.
Yes, further from shopping, but a 5-minute cab ride from Michigan Ave or a nice walk in good weather. It is also very close to the big theater area, so you could stroll over for a show.
And she might like to see nearby Macy's for a taste of the bygone huge downtown department store that is disappearing.
She can go to the Wit when she's 21 and can hit the fancy hip bar.