Must Dos
Shopping - Michigan Ave (Magnificent Mile), Macy's on State Street (that great street )
The Bean & The fountains in Millenium Park
The lakefront
Shedd Aquarium (get there early)
Lincoln Park Zoo (it's free)
Museum of Science and Industry (they have an area especially for crawling babies in the Ideas Factory. DS loved it). You can get the Metra from downtown (Randolph St) for a couple of $ - get off at 57th Street (they have an elevator). Stop for coffee/ gelato at Istria, under the railway arches by 57th street station.
Architecture boat ride
Children's Museum at Navy Pier . If at Navy Pier, you should really have a Chicago style hot dog. Or Fried Dough.
Places to Eat
The Cheesecake Factory , but long waits and you can't book, so get there early. They do quite good brunch Their sister restaurant,
Grand Lux Cafe is great too, but again, get there early. Fab choccie cake
Eduardos or
Giordano's for Chicago-style pizza
There are lots of other 'nice' restaurants too & diners - Bistro 110, Johnny Rockets... can give you more info nearer the time, if you like. For menus, look at Shedd Aquarium 0
Other places worth a visit:
You really should have a look in the Shedd Aquarium 1 shop - I've never seen anything quite like it. Start saving now - the dolls are $80 EACH
Shedd Aquarium 2 (they have a kids area but your DD may be too young to appreciate it)
Shedd Aquarium 3
Have a look at the museum websites - most have free days/ evenings every week or month.
You can walk to most places and there are plenty of taxis and buses. There is also a free trolley that serves most of the touristy places. You could also do one of those double decker bus tours.
If you like architecture, then have a look for Frank Lloyd Wright stuff in Oak Park & Hyde Park.
HTH