Quick trip through town
I don't know if there's any "hype" about Hackney's, but I think there's a lot to be said for a restaurant that delivers consistently dependable (solid, if not the best in Chicago, hamburgers), often interesting items (onion cake, differing specialties with an occasional Gallic twist), with a good selection of imported beers at a mid to low-level price range. Certainly not a destination site, but if you're in or near the South Loop, and are looking for a family-friendly place, and are not interested in ratcheting up the bill to the level of a Custom House or Gioco, Hackney's is certainly one of the better alternatives.
Hackney's is a local chain famous for its burgers and its "brick" of onion rings. The downtown location:
733 S. Dearborn
Chicago IL 60605
Actually, as long as the weather isn't that bad, you could walk between the Field Museum and Hackney's pretty easily, if you'd like to avoid paying twice for parking. Hackney's is about half a mile west and half a mile north of the Field Museum. Another option is to leave your car in one place and take a cab.
Another possibility not too far from the Field Museum, for breakfast and lunch only, is Orange on Harrison. They have eggs and pancakes, as well as salads and sandwiches for lunch:
Orange on Harrison
75 W. Harrison St.
Metromix listing - http://metromix.chicagotribune.com/di...
How about pizza?
For stuffed pizza, Giordano's has a location in Rosemont, near O'Hare:
9415 West Higgins Road
You may want to phone ahead from the road to order your pizza; the large stuffed pizzas take 30-45 minutes to bake.