Heidelberg

I really like Heidelberg and I am not sure what "Americanization" Rick Steves could refer to. Former military base, maybe?
I stayed in the old town a few years ago (Gasthaus Backmulde) but many streets are not really an option with a rental car. You need to search for accommodation with parking, and work from there. Booking.com has such research filters.

I didn't stay very long in Heidelberg as I was doing a drive from there to find the town my family came from. But I second the suggestion you find accommodations with designated parking. I stayed near the train station (not great area, but convenient to my rental car place). There was not much street parking, so I was thankful I didn't have to park near my hotel. Side note, on my big drive I went to Bad Wimpfen at the recommendation of someone on this forum - it was a cute little town with fachwerk houses. You could swing by on your way to your next stop from Heidelberg.

I didn't see a lot in Heidelberg, but I did take the funicular about half way up to the castle for a great view. I would have gone all the way up but there was record rain at the time I visited, the flooding/water issues closing many things including the funicular and the castle (hopefully that won't be the case for you). I strolled around the main pedestrian area that was very lively with students and people, great vibe. I enjoyed looking at the modern stained glass in the Heiliggeistkirche. My only big meal was at Palmbrau Gasse, where my notes say I had an "excellent" meal (grain of salt, I'd been driving all day through the German countryside and on the autobahn, pretty sure that was partly the giant glass of beer talking). Good luck planning your stop!

Heidelberg has a very nice and interesting old town area. And of course there is the castle. Definitely worth a short visit. Can't speak to the hotel issue as we always day tripped there when living close by.

We stayed there 2 nights.
https://photos.app.goo.gl/AZZyB3c5DeNuNrMo7

I think the last time Rick was in Heidelberg was 35 years ago. The base closed about 20 years ago. The city is filled with tourists from every country, including tons of Germans. Kind of sad that he doesn't revisit any of these places that he disses in his book. He might change his mind and his comments.

It is an interesting city and deserves at least a day or 2. Visit the castle riding the funicular up to it, the Pharmacy museum there, the Student Prison, the Philosophers walk, the main church and the Jesuit church for the main sights.

Hotel Anlage is a little quirky, but in a good location and they have several parking spots. You must reserve ahead for parking and there is a fee. Several of the parking garages in/around the Altstadt have 24hr parking. I was in Heidelberg while in the Army 1998-2000 and loved it. As mentioned the last US instalation there closed over 10 years ago. I used to visit almost every year, but kind of over did it and haven't been back for a few years. Good public transportation in and around Heidelberg.

Thank you all for the responses, it is appreciated!

Another vote for Heidelberg. I went there first in 1971, stayed a few nights in the DJH hostel.

Why was this city part of my itinerary in Germany then? Everyone else was going there, plus I had some real historical reasons too. Heidelberg was one of the larger cities that escaped horrific war damage.

Regardless of the viewpoint (irrelevant) expressed in the guide book, go to this famous city, the university is the oldest in Germany, but not in Central Europe.