Help for 1st timers in Germany

Rothenburg is best seen as an overnight trip after day-tripping tourists are left and so you can take the Night Watchman's Tour. And even Rick Steves admits it's a good place to shop for Christmas tree ornaments.

You will spend 6 hours on the train for Berlin - Bingen and another 5 hours on the train for Bingen - Munich... 11 hours total. This detour to Bingen really doesn't make a lot of sense IMHO considering...

a.) Berlin - Munich takes only 4 hours.
b.) The Rhine detour will force you onto the train for an 7 additional hours, all for the Rhine Cruise, which really only takes about 2 hours (or less.)

"Does anyone know of any other quaint medieval town close to Munich that are equally as appealing?"

Rothenburg is actually not near Munich at all. But it is fairly close to Nuremberg, and isn't too far off the Berlin - Nuremberg - Munich train route. So I would suggest that after you leave Berlin, you travel directly to Nuremberg first (about 3 hours from Berlin) and drop bags at a hotel near the station for 2 nights. Visit Nuremberg's old town and craftsmen's courtyard after checking into your hotel:

https://munique-tours.de/private-tour-guide-munich-bavaria/Nuremberg-from-Albrecht-Duerer-House.jpg
https://www.schloesser.bayern.de/englisch/palace/objects/nbg_burg.htm
https://www.youtube.com/watch?v=mU7qmhO5uwM

Then after breakfast the next morning, leave bags in your room and do a day trip to Rothenburg (if you wish) by local train. It's only about 1 hr 15 minutes from Nuremberg each way.

Then when you leave Nuremberg in the morning, you have only an hour's ride into Munich by direct train.

I will say that Nuremberg itself is a very charming place that you might like, even without a day trip to very touristy Rothenburg...

Walking tours
Museums
Nuremberg pubs

Nice old-world towns near Munich include Regensburg (UNESCO World Heritage medieval town) as well as Landsberg am Lech and Landshut.

Re Bayern Ticket, best bought out of a vending machine on the day of travel.

If you are going to be in Berlin for a week, consider going to Sachsenhausen and/or Ravensbruck Concentration Camps instead of Dachau. The Soviets used these as prisons so many of the buildings are still intact. Having visited all of them, I found the exhibits and presentations more interesting in these 2 rather than the ones in Dachau.

There are tons of towns like Rothenburg, just look at the Half-Timbered route to find them. Most of them are original too, rather than rebuilt like Rothenburg was.
https://www.deutsche-fachwerkstrasse.de/en/Homepage.html

Rather than the train Berlin to Bingen, take the fast train to Frankfurt instead. It is only 4 hours. From here, you can take a regional train to the Rhine and do your day trip on a ship. I like leaving from Rüdesheim instead of Bingen, and take the ship to St. Goar. Train back to Frankfurt. The train to Munich the next day is only 3 hours.

This looks like another case of "visit only the German areas covered in detail in the RS book" syndrome.

As others have said, Bavaria, the Middle Rhine, and Berlin are basically at three extremes of Germany, so you'll spend a lot of time travelling. In June you should have reasonable weather anywhere, so after Berlin try visiting some of the better preserved Hanseatic towns in northwestern Germany such as Luebeck, Lueneburg or Stralsund.

Or from Berlin go to the Harz Mountains in virtually the centre of Germany. Not really an "unspoilt" location as it has a lot of tourists from elsewhere in Germany, but not so popular with foreign tourists due to the lack of a nearby international airport. Lovely countryside and the towns of Wernigerode and Quedlinburg are beautiful - stay in one and visit the other.

I am asking myself how someone give advice to skip mid Rhine Valley for Rothenburg odT (incl. Romantic Route). These two are really not comparable neither by landscape and architecture nor by history and culture. Both beautiful on its own but very different.

1. See answers to your question on TA forum.

2.A) As mentioned in other forum you can stay on opposite side in Rüdesheim.

2.B) What do you mean?

3.A) No.

3.B) Rothenburg is not on the way and not so easy to reach. On train connection to Munich you will pass closer villages of Romantic Route. Go for on of these.

4) Zugspitze and Neuschwanstein Castle area 1-2 day trip from Munich. The scenic area close to Salzburg is likely National Park Berchtesgarden on German territory.

FU-A) Depends on your non-mentioned criteria.

FU-B) See tips you received on TA forum.

"I am asking myself how someone give advice to skip mid Rhine Valley for Rothenburg odT (incl. Romantic Route)."

FYI... my favorite place in all of Germany is the Middle Rhine Valley. But the OP apparently has planned a very short visit there (only a Rhine cruise is mentioned,) a visit which requires a disproportionate amount of additional train travel time and expense. So the purpose of my advice was to address the OP's other stated travel goals, which include Rothenburg. This advice is NOT a statement that Rothenburg is somehow a better destination than the Middle Rhine Valley OR a suitable substitute for the Rhine Valley experience. IMO it's not.

Stay in Bingen area and sightsee and do KD river boat
A) is there a better area to stay?

B) which is better train station to use?

I would stay in St. Goar (I actually have). It's a short trip (30 min, 7,30€) to Bingen Stadtbhf near the KD dock, and with the train ticket you get a 20% discount on the boat ticket. Ride the boat back to St. Goar; that's the most scenic part of the Rhein.

There are two stations in Bingen, the Hauptbahnhof and the Stadtbahnhof. The Bingen Stadtbahnof is a short walk to the KD dock. The Hauptbahnhof is more of a transit hub, but you'll have to take another train to the Stadtbahnhof or walk a considerable distance.

I heard there is a lovely lake & mountain area not to far from
Salzburg but the person couldn't remember the name ??

Sound like Berchtesgaden. I'd stay there and take a bus into Salzburg for a day trip rather than the other way around.

How about bayern ticket for the 3 of us into Austria

"Into Austria"? The Bayern Ticket is valid to Salzburg only on the train line from Freilassing. No need to buy it in advance. You can buy a Bayern Ticket for the same price at a ticket automat the morning of travel.

You are still in the rough draft stage. Then I suggest after the week in Berlin head somewhere else, ie skip Bavaria and Middle Rhine.

From Berlin you go northwest to Hamburg, or Lüneburg and Lübeck, as suggest above.

Or, transfer in Hamburg unless you get the direct ICE train, to Kiel. The Kieler Förde is an interesting place. Up north I would suggest Schwerin (better to go from Hamburg than Berlin), Stralsund,

Another option after Berlin is to head south, ie a choice of small towns and cities her...Meissen, Halle, Dresden, Leipzig, Jena, Weimar. Naumburg an der Saale....all places connected to and involved in German cultural history.