Munich to Berlin via Luther sites

You just write "Berlin Airport". Actually Berlin has two airports (TXL & SXF), take care to address the right one.

Eeeep! I was so worried about getting everything correct that I forgot!
We are flying out of Berlin Tegel.

skip the reviews. I don't bother with them and certainly would not believe those reviewers commenting on a tour they could not understand.

1. it's Marburg, not Harburg. Harburg castle is nice, but not related to Luther. Marburg on the other hand is an important Luther site with a massive castle and and a beautiful old town, but quite a detour. If you want something closer to your route: Veste Coburg and Hartenfeld castle in Torgau, both related to Luther. Coburg castle is huge, and the old town picturesque, and Torgau offers the first Protestant church and several places related to Luthers wife. Or Schmalkalden, also related to the Protestant Reformation, between Coburg and Eisenach, which offers a very cute old town full of timber-framed houses.
2. I don't know if Eisleben is a must. The house billed as Luthers place of birth was built 200 years later, and the house billed as his last residence isn't the real building either, as it was discovered some years ago that he died in a house on the market square.
3. Wittenberg, not Wittenburg. If you travel with a satnav you would end up in a completely different part of the country...

PS: but if you're looking for English-speaking tours it will be difficult in all the mentioned places, since most of them are mostly visited by Germans. Some however offer audio guides in English.

Erfurt and Eisenach both have lovely Old World architecture in their historic centers. I don't know that you're going to have time to see it, though. Erfurt even has a merchants' bridge.

Eisenach is an important Luther site because of the Wartburg, castle on the hilltop outside of town where Luther hid out for several years when he had a price on his head. While there, he translated the New Testament into German.

If you really mean Harburg (which, as mentioned above, has nothing to do with Luther), you should stop in Augsburg on the way (60km / 37 miles west of Munich), which was an important site of the Reformation. Here Luther defended his Wittenberg theses at the Diet of 1518, here the Confessio Augustana was proclaimed in 1530 and here finally the Augsburg religious peace between Catholics and Lutherans was declared in 1555 (the date, August 8, is still a public holiday in the city).

The Carmelite monastery St Anna in which Luther lived in 1518 is preserved and there is a memorial to him in the cloister; the church, which is today half protestant half catholic, is worth seeing too. Only a few steps from the church there is a parking garage, so your parents won't have to walk far. (Parking garage St. Anna, Im Annahof 4, OLC-Code 9V9V+5H Augsburg).

Please allow one suggestion to mentioned later destination "Norway": have a look at stave churches.

Fred: Thanks for your comment. I thought that since the tours would mostly be in German; we will research as much as possible before we leave home.

Martin: Thanks for your comment. I did mean Harburg Castle even though its not about Luther. Joe is interested in seeing an old burg. We have both read about them and to see one would be very interesting. I am also interested in Veste Coburg and Hartenfeld Castle. I will definitely check them out and see about adding them to our itinerary. Also, Schmalkalden looks nice. I think we will skip Eisleben, that will free up some time. I need more hours each day.
I think I better be more diligent on the spelling, who knows where we would end up. It might be an adventure for me, but I don't think Mother would be amused!

acraven: Thanks for your comment. My original plan was to stay the night in Erfurt so we could see the town after the tour buses have left and before they arrive in the morning. After reading your comment, I think I might have to massage the itinerary!

Sam: Thanks for your comment. I think Eisenach is a definite must see.

sla019: Thanks for your comment. I will put Augsburg on the list of must see. There seems to be much Luther history there. The fact that parking is close is a plus.

MarkK: Thanks for your comment. I would absolutely love to see a stave church. Sadly, there are not many left. Unfortunately, we will be to far north, We will be staying at friends and going to church meetings. We will be flying from Berlin to Stockholm (2 nights). Stockholm to Kiruna (2 nights, friends and important sites of Laestadius movement). Driving to Narvik, NOR (4 nights), Bjerkvik (3 nights), Leknes (2 nights). Drive back to Kiruna, SWE return rental car and fly home.

@ kh...You're welcome. I don't read reviews, don't use them , etc since I rather make up my own mind, most especially when it comes to German cultural and historical sites, and, above all, the reviewer does not presumably have a good level of reading or understanding German.

As suggested above, I do also recommend Marburg an der Lahn, not only to see this lovely town, this famous university town, especially in History, but also the Elisabethskirche in connection to Lutherianism. I went to Marburg the first time in 1977.

So, it's really Harburg castle. Sorry, my impression was that you are looking for Lutheran sites only, that's why I thought you confused Harburg and Marburg... ;-)

Well, if you are looking for a true, medieval- looking castle Harburg is a good choice, but I think Veste Coburg is more impressive. Have a look at the German Wikipedia article, which has a few more pics of the castle.
And Wartburg castle isn't too shabby either.

If you decide to see Coburg instead you could use one base for Eisenach (Wartburg), Erfurt and Coburg, which means more time for sightseeing. Maybe you could even squeeze in Weimar or Schmalkalden, or maybe Mühlhausen, if you're familiar with (and interested in) Thomas Müntzer and his role in the Protestant Reformation.

For the Wartburg Castle, it is still quite a walk up the steps from the parking lot to the actual castle, but I do see there is a shuttle service for elderly and disabled.
https://www.wartburg.de/en/my-visit/location-directions-parking.html

I hope you have time to visit the deconsecrated Synagogue in Erfurt. It has nothing to do with Luther, but it is an exceptionally old and historic building. It is mainly about medieval Erfurt, including the woad trade, and not just a "Jewish Tourism" site. It's an exceptional indoor visit in a town mainly known for its' exterior streetscapes. Note that Luther frequently visited Weimar, which you will be very near, and it's a wonderful visit, with more than you can see in one day. (We combined a lesser interest in Luther sites, with Bach sites.)

I personally would not fly to Munich if my next stop were Eisenach, but you get to decide your priorities. We enjoyed Munich, but saw it from an Austrian (by rail) vacation. Maybe you love driving more than I do. Note that a second flight segment (say, Munich or even Hamburg) on your overseas carrier's partner airline can cost little or nothing extra. We no longer avoid two-segment trips to Europe because they save time and money.

Note that Luther frequently visited Weimar, which you will be very
near, and it's a wonderful visit, with more than you can see in one
day.

And Lucas Cranach the Elder, who did most of the "propaganda" during the early days of the Protestant Reformation, lived there. His house still exists, just like his tomb.

Thank you everyone for your comments. After much discussion with Mother and Joe, We have decided to keep the itinerary we have with a couple of exceptions if it works. We would like to stay July 17th (night #1) in Eisenach, July 18th (night #2) in Erfurt, and July 19th, (night #3) in Wittenberg.

Any recommendations on hotels in these areas?