I am originally from NW Indiana. When back there visiting relatives I like to go to Riley's Railhouse in downtown Chesterton/Porter. The Railstream website has a free web camera there so you can watch online to see what you think. I believe you will see NS, CN, UP, and the Amtrak Capital. The owner of Riley's Railhouse, which is an old New York Central freight station converted into a bread and breakfast, is very much into trains and a very nice fellow. You can park in his lot to watch trains on the double track, and be sure to go inside and say hi. The inside has a running G scale train and is very nicely restored. He also has cabooses, which are painted to be South Shore (CSSB) orange and I believe a boxcar. The link to the Railsteam web page is https://railstream.net/live-cameras, pick Chesterton. Railstream has a link to Riley's Railhouse which is http://rileysrailhouse.com/. I believe next door is the old Chesterton passenger station.
The last interurban in the US also goes through Chesterton, the South Shore. I rode from the Dunes Station, by the Dunes State Park, off of US 12 in Chesterton to the South Bend Airport when home last. Being 65, I got the senior discount which was 5.00 each way. The South Shore ride takes about an hour each way and runs through the street in Michigan City Indiana which is pretty cool. You can checkout the South Shore schedules online at https://www.mysouthshoreline.com/. I think I rode it on a weekday and left Dunes Station at around 10am CST (Chesterton time) and got to South Bend about 12 something EST (South Bend time). Had a cup of coffee in SB and then back on train 30 or 40 minutes later for return trip. Schedule might change so check the latest if you are interested.
In Monon Indiana, which is about an hour or so south east of Valpo, is the Monon Connection Museum. Very nice private collection, open to the public. I think charge is 8 dollars to go into Museum. Has a nice place to eat next door called the Whistle Stop. Museum curator Harold, I think his name is, is an expert on the MONON railroad. He might just work weekends though. You can checkout the Monon Connection at http://mononconnection.com/
Hope this helps, sorry to be long winded. Have a nice trip, and if any additional questions I can help with let me know.