Thanks for the help, everyone. Ended up going to Avec, Agami, and Quartino late night after Lollapalooza. I would say that Avec was excellent, Agami was very good for what it is (though the atmosphere is not my style) and Quartino is solid but unspectacular. For lunch/brunch, I went to NoMi, Al's #1, and Aigre Doux.
Best food: Avec
Best atmosphere: NoMi
Best service: NoMi
Best dish: shrimp salad at Aigre Doux
Biggest disappointment: so many Chicago restaurants not being open late night, or on Sunday or Monday