Hi, Gerry, I think you've been getting some excellent advice.
If I may add a few grace notes: South Bend is indeed difficult to do as a round trip, particularly since, as had been said, the CSS&SB terminus is on the edge of town and that surprisingly small airport has no commercial service that I know of; and getting into town requires a cab.
South Bend certainly has its share of civic pride, but (as has unfortunately happened with so many American cities 1960 to present) the downtown is a shell of the commercial center it once was, now that cheap cars, good roads and cheaper gas have encouraged so much commerce to move away from the center city. Mishawaka, a northern suburb, has a knockout climatized shopping mall with a Macy's, and there's a pretty good strip center toward the east side of town. These destinations are doable by bus, but it is more difficult than with a car.
My own best use of downtown South Bend was to use it as a transfer point since all the local bus routes "tie up" there, and are scheduled as such to permit simultenous transfer -- thus eliminating the chance that one would have to wait for the next bus on the next route. This is especially a good thing because bus routing, while fairly comprehensive as to geography, is skeletal time-wise: about once an hour on Saturdays if I recall correctly. I had a very plesant weekend there using the lines but I was alone, at that time had no car, the weather was beautiful, and it was a perfect time for larking about. Even then, I couldn't make it to the most historic houses or the old Studebaker works.
Unlike so many larger American universities with their "fraternity rows" or "student ghettoes" that abut the high streets, Notre Dame has no periphery of privately-owned pubs or taverns and is pretty much an entity unto itself. It is on the north side of town, requires a bus trip, and you'll pass no pubs or cinemas or bookstores enroute. This is not to say you won't be welcome on campus there, but the casual bonhomie of undergraduates mixing with tourists in private establishments is not to be found. This makes it hard to just hang out and talk to people. The campus is undeniably beautiful, with an emphasis on Indiana limestone, and some truly impressive buildings -- the Hesburgh Library in particular is worth a look-see. There will also be found one of the most-visited grottoes in North America. But if Notre Dame is holding one of its spectacular at-home football Saturdays, don't go near the place. Suppose you and your wife wish to visit Notre Dame / S.B. at some other time? Probably the best way to spend the night convenient to campus is to book (ahead) a room at the university-owned Norris Center, a kind of small hotel in very solid shape that is right on the edge of campus.
Lastly, I'd like to put in a plug for an activity that can be done on a whim -- Indiana Dunes Beach State Park. The CSS&SB has a flag-stop there just a stop or two beyond Chesterton, and it is about as easy to walk from there to Lake Michigan as it is to walk from 11th Street/Mich. City to the Outlet Center -- once you've allowed for the fact that most of your hike will be on sand and that since we have had a very mosquito-prone summer, some repellent is not out of order. Water quality and temperature can vary, but any of the times I've visited the Dunes, there was an interesting and eclectic mix of people. Also, from about 8:30 to 12:00 on your left side you can see the curved skyline of most of Chicago -- starting with the southern and southeastern parts most tourists don't know about; and then culminating in the towers of downtown.
This time of year, night comes early and suddenly, but perhaps then you could make use of one of the South Shore's most oldest and charming traditions when you're ready to call it a day: "Passengers use light at night" to alert the engineer (motorman?) that he needs to stop the train for them. So you would not be out of line bringing what I believe you British call an electric "torch" just in case.
Happy street running! (Did you know they're talking about eliminating street running in Mich. City?) Enjoy your trip and America needs the revenue! - a.s.
