Hope you enjoy your stay here during the most brutal of our months weatherwise. Comfort food is always a great way to ward off the chill of a January deep freeze.
Chicago has an abundance of great steak houses. Keefers is among that group. However, if I was to choose one which would be a great standout in comparison to the others, it would be David Burke's Primehouse. You can find many reviews herein from our very knowlegeable community members by using the search function. Or simply google David Burke + LTH + Chicago.
For Mexican, there are so many options that you won't find in other cities. For great tacos, try La Pasadita on the east side of Ashland. Note: There are three on the same block. The east side location is the better of the three IMO.
If you enjoy a more traditional, but simple mexican meal of say Chicken in mole, it's really hard to beat Taqueria Oaxequena on Milwaukee or Cemitas Pueblas on North Avenue for excellent tacos and cemitas (try the milanesa).
There are a couple of good Pozolerias on Fullerton Avenue near Pulaski that serve hearty and traditional dishes. My favorite being San Juan.
Folks here generally rave about the Yucatan specialties at Xni-Pec, and I agree. From wonderful seafood dishes to the incredibly rich slow cooked pork dish, conchita pibil, everything at Xni-pec is fresh, unique and delicious.
If you like Thai, Chicago has a number of excellent options including TAC, Sticky Rice and Spoon Thai.