It's a fantastic city. I visited earlier this year. It's very easy to get around.
Treat yourself and take an architectural boat tour. Also, visit Lincoln Park Zoo (the zoo is free).
And, of course, Wrigley Field or just Wrigleyville. Make a stop at Murphy's and have a drink.
I was able to make a Cubbies game and sat next to an 80+ year old guy that became a Cubs fan when he was 10 years old and first saw them play in the in 1945 World Series. Tons of knowledge/history dropped on me during that game. He remembers when tickets were $0.25. hahah. It was quite an experience.
Oh... and the food. So many great places to eat.