Couples Trip: 4 countries in 2 weeks

I was hoping to find a castle like Neuschwanstein and a palace like
Versailles nearby but Ludwigsburg Palace and Schloss Lichtenstein seem
too far to do as a day trip. Any other ideas that are closer?

??? Ludwigsburg is a 10-minute train ride from Stuttgart's main station. Not that I'm suggesting you stay in Stuttgart, which is not a good springboard for the Black Forest. Gengenbach is vastly different from Stuttgart. it is IN the Black Forest region and quite a nice little place.

Neuschwanstein is "Schloss" (palace) Neuschwanstein, not a castle at all. You won't find anything that is like Neuschwanstein (late 19th-century palace with a fake castle exterior.) With a change of plans, you CAN tour a genuine medieval castle on the way south from A'dam. "Burg" (castle) is usually part of the castle name. Near Koblenz are these two:

Marksburg
Burg Eltz

Similar options near Koblenz:
Rheinfels
Reichsburg

Castle-hotels near Koblenz:
Auf Schoenburg
Burg Liebenstein
Burg Reichenstein

I lived in Stuttgart for 8 months. It is not a great city to explore. It was severely bombed in WWII and aside from the Porsche and Mercedes museums, not a great tour place.

Also, the city is spread over a large area and traffic is very heavy. Suggest skipping Stuttgart.
Consider taking the train to Strasburg, France to spend a day visiting that great city before or after the Black Forest.
If you do the Black Forest first, take the train to Baden-Baden or Friberg.

If you are looking for a fairy tale castle in the Black Forest, I would recommend Hohenzollern, for the location if nothing else: https://burg-hohenzollern.com/en/

I agree that Stuttgart isn't the best place to stay. We stayed in Baden Baden and Freiburg- both very nice but I preferred Freiburg. Very quaint with a lovely square to sit outside and eat dinner in.

...they’ve only done it on a cruise ship. I’m trying to replicate a cruise style trip, but using trains and a car instead.

In one afternoon, you can enjoy the same dramatic river scenery your companions probably did on their river-cruise trip - see video below - on a cruise that takes just 4 hours or less. It will take in some of the castles mentioned in my previous post:

https://www.youtube.com/watch?v=_vDJzhB7M8c&t=66s

The part between Bingen (in the south) and Koblenz is the best. Cruise area map:

https://i.pinimg.com/originals/6e/5c/d8/6e5cd87b4b97495a0574654a1712b73a.gif

I should have mentioned the KONUS Guest Card. Gengenbach is one of many Black Forest towns which provides FREE train transportation all around the Black Forest to its guests. You receive the card when you check in - use it like a rail pass on any regional trains you like... It's valid to Freiburg, Triberg, Gutach (where the summer bobsled/coaster is located) and anywhere else you wish to travel to in the Black Forest. See Map:

https://www.youtube.com/watch?v=KkgzMXQ7blQ

Burg Hohenzollern: There once was a medieval castle on the hill top where today's Hohenzollern palace (also built in the late 19th century) was built to replace it. It's not in the Black Forest however - it lies to the East in the Swabian Alb region.

I don't have many specific recommendations, just a couple of comments:
1. I took a couple of cruises with my family when my parents were alive, and the thing I liked about them was that everyone could do their own thing in port and meet back on the ship for dinner. Choose places to stay that have lots to offer everyone (like Amsterdam, great choice) and allow everyone to make their own choices about activities. Since you don't seem to know what your in-laws ARE interested in (you only mentioned what they are not into), it doesn't make sense for you to plan their activities for them and even less for you to expect them to participate in the activities that you plan. And mix it up. Maybe the two brothers want to have some time together while you and your sister-in-law enjoy something girly (like the Mouse Museum, aka the Sam and Julia Shop, in Amsterdam).
2. The Red Light District? I really don't understand why anyone would want to do this, but if that's your thing, knock yourself out.
3. Definitely stay in Amsterdam so that everyone has all the options immediately available.

Thanks for the feedback. To clarify, we don’t plan on staying IN Stuttgart, just arriving there from Amsterdam by train. I phrased my question poorly. I am looking at basing ourselves in either Gengenbach or Staufen.

Hubby and I prefer small towns (past favourites include GP, Bacarach, Rudesheim and Rothenburg ob der Tauber) to larger cities, so not sure Strasbourg or Freiburg would be ideal for us.

@Russ: I swear that I saw Ludwigsburg as 2.5 hours from Gengenbach but when I Google map it now it’s only 1.5 hours, so very doable. Thank you for the suggestions for the various castles. I should have mentioned that my husband and I have visited Germany before and visited Burg Eltz ( I loved the hike up to it even more than the castle itself). I am certain that we used your advice on these boards extensively to plan our Rhine trip. The highlight for us was biking from our hotel in Bacahrach to Rudesheim and taking the river cruise back. Thanks for the tip about the KonusCard

CatVH, I will take a look at Hohenzollern. Thank you.

G3RRYC: Great points about mixing things up a bit. I love the idea. I believe there is golfing in Baden Wurttemberg and maybe the guys could do while the ladies do a wine tour.

The red light district that I would want to do is the walk and talk with the sex workers to hear their perspective on their profession and challenge my own. Thanks for weighing in on where to stay in Amsterdam.

Lastly, I am looking at Switzerland primarily because we need a place that’s not too far by car or train with a direct flight back to Toronto. I suspect that we could get a similar (ish) experience (and save some money) by spending those days around Lake Konstanz/Bavaria and fly back from Munich instead.

We liked Haarlem a lot, and it is very close to Amsterdam and the airport by train. It also is a little quieter if you need a spot to get over jet lag. It is a site worth seeing itself and you could consider trading the Anne Frank house for the Corrie ten boom house, and renting your bikes there. I'm not sure I would stay there only because it is cheaper, if all you will do is daytrip in everyday.

(My suggested but unhelpful stop on the Rhine: sorry, didn't remember your board name...)

I was hoping to find a castle like Neuschwanstein and a palace like
Versailles nearby but Ludwigsburg Palace and Schloss Lichtenstein seem
too far to do as a day trip. Any other ideas that are closer?

Ludwigsburg and the MB museum, with the travel time, are too much for a day that starts and ends in G'bach, IMHO. Rather than backtracking from Gengenbach to the Stuttgart area for Ludwigsburg and the MB museum, why not just go there directly from Amsterdam? I'd add a brief stay in the area as follows.

• morning time in A'dam

• 12:38 - 18:28 train to Ludwigsburg for 2 or 3 nights. Ludwigsburg is a smallish town, with the palace and accommodations near Ludwigsburg station. And it's a good base town for your sightseeing goals. Stay there, and you won't have to deal with Stuttgart other than just to pass through it. See the palace at your convenience... also...

• Take an outing from Ludwigsburg > MB Museum (25 min. by train, station is Stuttgart Neckarpark.)

• Take another outing to the gorgeous little wine town of Besigheim (12 train minutes from Ludwigsburg)
  https://placesofgermany.de/wp-content/uploads/2023/04/Besigheim-Altstadt-5.webp
  https://www.youtube.com/watch?v=M1xqGvinerc

• Esslingen is another great old-world Neckar River town and daytrip option (a direct 29 min. train ride from L'burg.)

https://www.esslingen-info.com/en/discover/sights/top-10-of-the-sights

Then move on to your base in Gengenbach.

Thanks very much for the added info, Russ. Those two towns look so charming!

The main reasons I chose Stuttgart was because I wanted a direct connection with Amsterdam. As it's only 1.5 hours each way between Gengenbach and Ludwisgburg, and we love a good road trip, I am going to see if I can find a scenic route between the two. I appreciate the suggestions though and will save them for future trips.