Unless you live in the Northeast Corridor, I have found Amtrak to be useless. It’s no faster or less expensive than bus travel and serves far fewer cities.
Milwaukee to Chicago Hiawatha service is absolutely wonderful. $42 roundtrip - I get a full days worth of work in even when running down for meetings or conventions. Oftentimes very full during the week. A great line.
Problem is the politicos want to bloat the area with their own interurban lines as well. Milwaukee to Kenosha, Milwaukee to Racine; lines that are almost redundant with Amtrak stops.