Hi all, and thanks for your great suggestions. We loved Chicago (in fact we stayed two nights longer than planned) and hope we'll be back!
Here's where we ate, broken down by meals. Overall we ate very well while in Chicago. We spent the 4 first nights at the Palmer House hotel and the last 2 at the Sofitel O'Hare.
Corner Bakery - nothing to write home about. Toast, yogurt and granola, so-so coffee
Orange - probably our biggest disappointment - and most expensive breakfast - of the week - food wise. I had eggs and orange and rosemary sausage. It was good, but not worth the $. SO had the steak benedict on brioche, and really didn't like it.
Au bon pain - we went there after doing a lot of walking around and finding out that there was a huge line up at Orange. I was hungry and would have eaten just about anywhere - which is what it was, in the end. Really not great - on par with Orange - but at least a bit cheaper.
Colette at Sofitel - absolute best breakfasts while in Chicago. They bring you a complimentary basket of croissants, danishes, brioche, baguette (probably 6 pieces in total) and tiny little glasses of smoothie along with your ordered breakfast. It is not a cheap breakfast, but so worth the money.
Because we had huge - and often late - breakfasts, we didn't really have a lot of lunches out at restaurants. Rather, we ate granola bars/fruit, etc.
Blackbird - great, if a bit on the snobbish side. I had the porkbelly sandwich (very good) and what I think are the best french fries I have ever had. SO had the bouillabaisse. We shared the Crémeux à l'avocat (a pudding-panna cotta like concoction of avocado and cream, served with chartreuse granité and chartreuse-macerated blueberries. Very good, and definitely different.
Museum of Science and Industry's Brain Food Court - Museum food - need I say more?
Adler Planetarium's Galileo Café - actually not bad - I had a pulled pork sandwich and really enjoyed it. Nicely seasoned barbecue sauce, warm and soft bun. Quite good.
Giordano's - Our first meal in Chicago, after driving for 10 hours. We had the special stuffed pizza and it was very good. I liked how all components tasted like what they were and how fresh tasting and non greasy the pizza was. SO found it ok, but not exciting.
Park Grill, in Millenium Park. SO had steak and frites - very good but too salty, he said, and I had the melon gazpacho and the tuna on pea shoots - very good and light. We shared the baked chocolate mousse, the tiniest dessert we ever had, but it was good and very chocolate-y.
Berghoff, in the Loop. That's apparently a Chicago institution and was recommended by a friend, in a 'if you go to Chicago and like hearty meals, go to the Berghoff' way. It was all right, nothing spectacular. Their amber beer was really good, as were the vegetables, which were not overcooked and were very lightly dressed.
Green Zebra. Wow! This was my best meal while in Chicago. We both had the 5-course tasting menu: fried green tomatoes with chevre and a balsamic reduction, thai-influenced carrot soup, braised abalone mushroom with arugula, ricotta-lemon gnocci with figs, and funnel cakes with raspberry float (lemongrass ice cream, strawberry sorbet and raspberry soda). We had a Goose Island beer (great, Belgian abbaye style beer!) and I had a pink peppercorn and thyme soda (way too sweet for my taste, but very good once diluted with water). There was a mix up at some point and they brought us a walnut soda and a bitter lemon soda on the house. And they did not charge us for the beers. Nice attention indeed.
Other food-related experiences:
Trader Joe's: it was my first time there, so I of course I liked it and brought back some good stuff to Canada: chocolate, dried fruit, fig granola bars, blueberry granola. But my best discovery was the great Fage yogurt - OMG! We had it with granola and fresh fruit at the hotel for breakfast one morning.
Fox and Obel: great foodie place. We went to see Cirque Shangai at Navy Pier and bought a picnic at F&O: smoked duck breast, baguette, beet and chèvre salad, sweet potato salad, grilled asparagus, chocolate mousse and banana cream pie. Need I say more?
Like I said, we had an amazing time in Chicago, and had great food. Thanks for your great recommendations, and looking forward to returning!