Chicago, that town is great! Any of the museums are Top Notch or especially Shedd Aquarium, we missed the Planetarium. Shopping/experiencing some fine department stores a few minutes north on Michigan Avenue. The wife and I stayed several times out in the suburbs, jump on the interstate, Roosevelt Avenue or Ogden Avenue and drive west to the small towns. Check out the very crowded old McDonalds restaurant downtown on Ohio steet, it is something you won't forget. Downers Grove and many other towns have a semi-fast food joint called Portillo's and it is remarkable. A trip to the top of the Sears tower is pretty neat especially on a clear day. More shopping on Navy Pier.
Nice people, nice place for sure. Oh, if you drive the interstate be prepared to drive at least 85 and be ready to make snap decisions to make an exit.
Stay warm this time of year I don't know how my wifes cousins manage up north in Libertyville....Brrrrrrr.