One last input regarding your stopover in Chicago--
If you are leaving Chicago for Indiana on a weekday, wait until after 9:00 a.m. Getting in and out of the city is horrendous during rush hour, no matter what route you follow. Also, weather in March can be very changeable. We could have snow or it could be 70 degrees.
Joel's suggestion to take Lake Shore Drive is a good one. The Skyway is a tollway, however, so be prepared for the toll. I think it is a couple of dollars now. Also, once you hit the south side of Chicago, the driver is no longer beautiful--you will see the ugliest part of industrial Chicago and northwest Indiana. If you do not already know this, however, I-90 does not intersect U.S. 30. I am sure you will be getting directions from your family as to which road to take from I-90 south to U.S. 30.
That Howard Johnson's is AWFUL. Do not stay there. I suspect that you can get a cab and get checked in at the Raphael almost as quickly as you could get to one of the motels in the area of Midway. Also, the area around Midway has some quite iffy neighborhoods, and one of us locals would need to check the address of any place you might choose. It will not be any easier to get to the highway from that area than from downtown.
Take the cab to the Raphael. Arriving at Midway at 7:00 p.m. you should not hit too much traffic heading downtown. The airport shuttle is pretty good, but it is still a form of mass transit that I would not want to deal with after the amount of time you will have spent in transit.
Take a cab in the morning to either 400 N. State or 203 N. LaSalle. Those locations are only about four blocks apart with the 203 N. LaSalle (entrance is actually on Clark)being in the Loop. The cab will cost about $5.00, especially if you wait until after 9:00 a.m. From either location you can easily follow Joel's route to southbound Lake Shore Drive, or head a few blocks west to I-94 (In Chicago we call the southbound part of it the Dan Ryan Expressway and the northbound part of it the Kennedy Expressway. Sometimes Chicagoans don't even know the interstate numbers, and the traffic reports will all be referring to the names, not the numbers.)
On Saturday, traffic heading in to the city before about 11:00 a.m. is very light, no matter which route you take. Once you get to noon time, things start to get heavier. Also, I do not believe there will be anywhere to store luggage at Union Station, so do think about that when you are returning to Chicago. You might want to park the car with the luggage in the trunk until you are ready to leave.
Lisa in Chicago