So far the ideas brought up have not been very good (already did boat thing, done baseball game).
Any suggestions for a company outing that is:
A) Not more than $50/person
B) Kid friendly
C) In Chicago (or pretty close)
Thanks for suggestions in advance!
The Morton Arboretum, maybe?
WhirlyBall?
Dave and Busters?
The Untouchables Tour is a good time.
WhirlyBall you need to be over 12 and some of the kids are not that old. You can imagine what happens if the little kids are left on the side to watch everyone else drive bumper cars. 
Dave and Busters might be good.
Meuseum of Science and Industry is very cool and kids like it.
Shedd aquarium too.
CAF Boat tour http://caf.architecture.org/page.aspx?pid=574
The Oriental Institute (near-Eastern archeology) at the University of Chicago:
http://oi.uchicago.edu/museum/
Exotic enough to wow even children too small to know what they are looking at, and unlikely to duplicate school excursions. Near enough to park space (Washington, Jackson) for running around and/or picnics (ask around; some spots iffy due to problems in nearby neighborhoods). Other U of C sites may be added to the excursion, as well.
Even though it’s not unique to Chicago, if you’re including kids I like the Dave & Buster’s idea. The kiddies will be happy playing the games, and the adults have billiards and alcohol. Something for everyone.
Check out Great America. It’s a short drive up 94 and they offer really good group discounts. It’s also something that’s good for the entire family.