i was actually going to suggest Pizzano's, too. i had avoided the place until recently (read some mixed reviews)... i've gone twice lately... i love their deep dish. the people at the bar have been super friendly... i went once for lunch, sat at the bar, ended up staying for 2 hours just chit chatting w/ people at the bar. i'm totally not that type of person usually either.
... another you might consider is the recently opened "The Gage" (there's a thread somewhere if you search).. i was a little less than impressed with what i ordered but i i would give it another whirl ...
i would avoid the park grill/cafe ..
Tavern At the Park just opened this week. haven't heard if it's a yay or nay, but it's a keefers restaurant so i'm sure it's ok at the very least. but if you're going to lollapalooza you might be underdressed for it anyway.
then there's the random bennigan's or two, artists' cafe.. a lot of other places in the area are closed on weekends.
has anyone been to the cafe in the art institute courtyard? i never even knew they had a restaurant until recently. any good? it's a beautiful looking plaza
(is heaven on seven over on wabash open on the weekend? i assume so.