In Chicago, we prefer Connie's over Giordano's for Chicago-style pizza. Not that Giordano's is bad, but we order from them every time we're in Florida so they just don't have that "only in Chicago" feel any more. There's a French bakery/bistro near the Loyola downtown campus called Le Pain Quotidien that we absolutely love for breakfasts when we're in the city, and Yolk near Navy Pier is awesome for a heavier, American-style breakfast.
I'd second the recommendation for Wild Horse Saloon in Nashville. It was the only "real" meal we made time for on our last visit, since we were only there for one night and it was during the summer so breakfast & lunch both came from the farmer's market, and it was a really fun time, even for my not-that-into-country kids.