I think Eataly is heaven, just plan to go at an off-peak time and allow time to spend a few hours total between eating, browsing, and shopping. It's Disneyland for Italian food. Don't miss it! My advice is to go to the seafood counter to eat. It's less busy, you can usually sit right at the bar with the chefs and those fellas will take care of you. The last time I went there for lunch, they gave us a few tasting pours of wines they love and a few free nibbles of special things they were working on. It was a spectacular lunch. The pizza/pasta area is almost always nuts, so be open minded to the other areas and you won't be disappointed. And pick up some truffled red pesto sauce in the pantry section. Yeah, baby.

Looks like you're covered on restaurant recommendations below.

How upscale do you want it to be? The good restaurants will be full of people doing business lunches. Honestly that area of the city is filled with great options. Make reservations for lunch. They all get packed.

The Gage - great gastropub food, casual

Terzo Piano at the museum - not as formal as it might seem at first, reservation is recommended though because it gets packed easily at peak times

Seven Lions Chicago - Alpana Singh's restaurant right across the street from the museum, more upscale, need reservations

Lockwood - the restaurant in the Palmer House hotel lobby, stunning space, lovely food

Millennium Park's Grill - the food is solid and they have a nice patio that opens up into the park if it's a good weather day, also need reservations