This is a nice day trip but you want to ensure the lake conditions are suitable for your boat. You may also want a marine radio to talk to barges on the cal-sag and the obrien lockmaster. The only place to buy gas will be near the obrien lock on the cal sag or at burnham harbor (very expensive). You can run over to the Hammond Marina (only a few miles) as well for gas.
There is nothing better than the trip from the navy pier lock to river city. Its a great ride and really shows off the architecture of Chicago.
We have made this trip in out 230 as well as our cruisers. Good Luck.