The South Bend Airport is a small airport that has one of the best indoor observation areas that I have seen. It is a two story atrium in the center of the terminal, outside the security area so that non-passengers can come in. There are chairs on both floors facing the airside ramp with floor-to-ceiling windows. On the second floor there are old photographs on the walls depicting memorable moments in aviation in the history of this region and old photos of the airport. There is also a flight schedule monitor and control tower audio on the speakers. The airport has recently completed an expansion and modernization project to upgrade this 30 year old terminal and is the 2nd busiest airport in the state of Indiana.
The view faces the center of the main runway so you can see all of the traffic, but with the new concourse built on that part of the ramp it may block some of the view of the ramp. As for photography, you are facing north so it has pretty good light almost all year, except maybe summer evenings. The South Bend Airport is served by United Express, Delta Connection, and Allegiant Air with most of the traffic being regional jets; however, the view is superb. If you are traveling through the area I would recommend a visit here. In the photo examples below there is a picture of this observation area.