Thanks to all of you for your suggestions.
I intend to go to at least four of these :-)
In mid-July I'll meet up in Chicago with family (including kids 10 and 9) from England. We'll spend 3 days with a CTA pass visiting the downtown tourist locations (Willis and Hancock towers, Field Museum, Art Institute, Navy Pier, etc.) before we head to Union Station for an Amtrak ride to southern Illinois and elsewhere.
It's the first time in the US for the kids, so the tourist locations will restrict our willingness to travel a long way for lunch or a snack (dinner should be no problem as most tourist sites close by 5pm). But with a CTA pass I'm happy to ride a few stops for a "must do" food stop :-)
What good food options are available within a 10 minute walk of some tourist locations? We are up for any type of food, for both lunch or a snack. And pizza is top of our dinner list.