For a nice Italian spot downtown (by which I'm assuming you mean the Loop) I like Trattoria #10. The food is good, the room is pleasant, and they have a very nice bar buffet which is a meal in itself.
Even better food is to be had at Vivere, the haute-Italian restaurant in the Italian Village complex, but that may be more than you wanted to spend. The Cantina (I believe it's called), the lower level spot in the It.Vi., is casual and inexpensive. I've enjoyed lunches there, but never been for dinner. Stay away from the spot on the top floor ("the Village"), which is mediocre on a
good day.
South of downtown is Giocco, which is quite good - their octopus carpaccio is grand, and their pastas are no slouch, either.