I live in Chicago. My thoughts and recommendations:
- The architecture boat tour is awesome and a must.
- Yes, sit on the third base side of Wrigley to avoid the sun beating down on you. The Bleachers are very fun, but you're in the sun and it's a drunken frat party, so not kid-friendly. Big Star (Mexican) and Smoke Daddy (BBQ) are two good restaurants right next to Wrigley if you want to eat before or after.
- The Art Institute is world-class but not sure an 11 and 14-year old would enjoy. The Museum of Science & Industry is great and more likely to please your kids.
- Don't do the Willis Tower. It's a tourist trap that takes over an hour to get to the Skydeck (i.e., the top w/ the glass platforms that extend out and you walk on). You just go from one line on one floor to another for an hour+. The John Hancock Tower's 360 Observation Deck is much better.
- Like VT said, the West Loop has great restaurants.
- Cindy's at the top of the Chicago Athletic Association has an awesome view of Millennium Park.
- Lincoln Park Zoo is very meh. I find it depressing like most zoos.
- Rent bikes and ride up and down the path along the lake. Can't go wrong north or south. Maybe bring your swim suits and hit up a beach. Chicago's a beach town during the summer.