Train area seating choices

I looked at the route you want and those trains don't have compartments.

The leg between Koblenz and Cologne does. The first and last leg are Regional.

The only seating concern I can think of is that two long-legged people sitting across from each other at a table may be a bit uncomfortable. I'm quite short, and even I have to be careful about what I do with my feet when there's someone sitting across from me. I think sitting across from your child would avoid that potential problem.

I just spent 6 hours on a train yesterday in the U.S. Other than basic pleasantries, a lot of people are doing their own thing, reading, working, taking care of their kids, etc. I’ve done long haul in compartments and open air in Europe, and again, the only time I remember talking much was in the last stretch before Prague when I got up to stand in the aisle outside the compartment and chatted a bit with a fellow American who was also tired of sitting. Granted, I’m not gregarious, but real life is not always like a travel TV show. I bring this up not to sound cynical but just to mention that not everyone is chatty on trains a la Rick.

I took two very short train trips in September/October; one from Vienna to Salzburg, Austria and one from Pforzheim to Karlsruhe, Germany. Vienna to Salzburg was unreserved and on a Saturday, and the train was very very full, and I couldn't understand the line-up of cars, so I got on at the wrong end, and had to walk through two cars of first-class, a restaurant car, two cars of "reserved" seats, and finally found the 2nd class unreserved, which by that time, was very very full. I managed to find a seat, though.

I reserved an aisle seat at a table on the train from Pforzheim to Karlsruhe. Once again, the train was very, very full, on a Thursday, and when I found my reserved seat, there were already 4 people comfortably ensconced at the table.

Ha, I found myself a 2-seat combo which was not reserved, and just enjoyed the short jaunt.

In both instances, I found myself a rear-facing 2-seat combo, and if I were with my son, I would go ahead and reserve a front-facing 2-seat combo.

"I got on at the wrong end,..." You probably did not have time to check the "Wagenstandanzeiger." But that does not always work either since the trains sometimes don't stop exactly as indicated on the Wagenstandanzeiger, then it's a mad rush. Hopefully you did not have luggage when navigating through those coaches.

after seeing years of Rick talking to friendly locals

He's filming a TV series, the 'friendly locals' that he is chatting to have already been found and agree to be filmed chatting to him. For the most part people keep themselves to themselves and aren't inclined to chat with strangers. I don't recall striking up a conversation with anyone whilst travelling abroad (or at home) on a train. Sorry to sound cynical but that's just my experience,

I always make a reservation for opposite window seats with a table. It guarantees one seat facing forward. Trains can turn direction, and it can happen that the train has a different order than planned.

Train travel has changed a lot; I used to have great conversations with fellow passengers, but now most people are plugged into their electronic devices or reading. I wouldn't expect much conversation.

The table would be good if you plan to have a snack at your seat.

Slightly off-topic, but I do like the way French railway stations have a platform indicator to show where each carriage of a TGV or Inter-cities train is likely to stop. Then it's easy to find your reserved seat, even if you do board at the wrong end of that carriage. I've been surprised how few tourist travellers are aware of that provision.