I don't get it - you live in Chicago, and she's worried about not-driving?
Why don't you tell her how many kids have died as passengers in cars over the past year in Chicago, and compare that to the number who died on the bus/train/El?
I've taken all public transit modes in Chicago and have found them to be pleasant, efficient, stress free and fun. Maybe you should tell your sister to lighten up on the bus service and have concern for her kids safety - where is Mothers Against Driving when you need them?
BTW I have driven in Chicago too, and it's not been so bad either... Haven't been killed yet, even though someone tried on Lower Wacker (such a great name
).
Unfortunately I have not had the chance to ride in Chicago, but my understanding is that cycling is pretty good there too - maybe that is be your best option.
Finally - I suggest you take the kids to the museums, Chicago has some of the best in the world.