Following my fathers WW2 service

I don't have any specifics for that route, but is there an active association for the division your father served in? A friend of mine visited the France border with surviving service members to dedicate a 70th anniversary memorial in one of the small towns. The association for his father's division had excellent documentation of all the battle sites, service records, etc., and I noticed their web page even has current photos of battle sites. Worth a look to see if they might have resources to help you plan.

My late father was a veteran of the Pacific, so I can’t offer much in the way of WWII Europe, but I have had a good experience working with DH Tour out of Ontario. Sharing their battlefield tour page in case it’s useful. They’re more focused on Canadian & Commonwealth participation; however, they mention guides who lead small or private tours. Could be worth contacting them for recommendations. Best wishes for your trip planning.

https://dhgrouptours.com/coach-tours-rail-tours/battlefield-tours/

From a short research I recommend to have a closer look to combat sites of Operation Nordwind. After this there were no significant larger units of German army (e. g. Heeresgruppe) to fight against. Please do not get me wrong because especially Southern Germany had a lot of fanatic Nazi followers who wanted to fight in smaller groups until the last soldier died - sometimes themselves. German movie "Die Brücke" from 1959 addressed this behavior.

From what I know / read towns such as Stuttgart, Freiburg im Breisgau, Ulm, Augsburg (7th army) and Munich were not large battle grounds and partly already bombed into ashes before troops (together with French army) reached and occupied these.

Stuttgart for example had over 50 bomber attacks. 68% of all residential buildings and 75% of industrial facilities were destroyed. A total of 4,477 people were killed and 8,908 injured in Stuttgart. This is just an example - a lot of Southern Germany towns have such a history with different degrees of destruction.

I guess you already planned to visit former camp Dachau which was exempted by 7th US army (afaik).

Be careful when researching because likely some search results have German 6th army as content which was a drama on its own.

Good luck.

Look at super6th.org for information. Also try and find what unit your father was in within 6th Armored Division. You will get a much more accurate picture of what your father did or didn’t do.

This website might be useful:

https://www.fold3.com/

I lived in Augsburg, Germany (50 miles west of Munich) for four years (87-91) working for the US Army as a civilian.
It is a wonderful city to visit, over 2000 years old, named for Augustus Caesar. Recommend spending a day there.
Augsburg had half of its buildings destroyed or damaged. Also, there was an ME-109 factory just outside the city and you could still see the bomb craters from allied bombing where the factory used to be.

Also, I recommend visiting The Romantic Road, that goes through Augsburg and several scenic Medieval small cities and towns, most notably Rothenburg ob der Tauber.
https://www.romanticroadgermany.com

If your father joined the division around Nancy he was a replacement, and sent for the push from there across the Rhine. The main places you'll want to see are Nancy, Sarreguemines, & Metz. This is beautiful country today, and those towns are some of my favorites. You'll have to look around Nancy because there's not a lot of WWII stuff (memorials, etc.) in the city, but you can find some things in the small towns outside. In particular you want to swing over towards Arracourt, where a big tank battle was held and there's a memorial.

But if you take D674 from Nancy to Sarreguemines you want to pay attention because you can see several WWII German bunkers now sitting in plowed fields. There's one right near the road by the small town of Francaltroff. And just a little further down the road is an old flak tower. It's a beautiful drive when the weather's clear.

Sarreguemines has changed hands between France and Germany several times; you'll encounter signs with both French and German spellings of the towns name. It's a pretty place, not large. Not to far away, if you want to detour, is the Maginot Line at Fort Casso.

Metz is a backtrack, but you should go there. There's a nice memorial to the city's liberation right on the main square by the cathedral. From Metz take the main highway (A4) to Saarbrucken. On the way you'll see the signs for the American Cemetery at St Avold. I highly recommend you stop and visit this, it's the largest one in Europe.

Now I don't know where he rejoined the unit, but if you want to follow the Division your next point is the diversion to Bastogne, which goes from Metz to Ettalbruck, to Bastogne and Longvilly. This is a decent drive, not a attractive as the previous, and can easily be done in a day or two. (Much faster than the two months the 6th spent in DEC 44/JAN 45.)

After that the unit went south again to Zweibrucken, a city that once held almost 100.000 Americans until the Army downsized in Germany back in the 1990's. The city has not yet recovered from that loss of income. But you can drive from there to Worms; you'll go through the Pfalz forest, and there are still some reminders of the war in the area. I recommend you go from Zweibrucken to Bad Bergzabern and visit the WWII museum there on what's left of the Siegfried line. That's a short drive, maybe an hour, via Pirmasens.
You'll pass 5-6 castle ruins along that route, you may want to stop and visit Berwartstein Castle.

From there it really depends on what you want to see en route, because if you head to Worms, you pass through either the Pfalz forest, the German wine country (on the Winestrasse), or the major historical cities of Landau, Speyer, and Ludwigshafen along the river. There's a huge amount of things to see and do in that region.

North of Worms you want to drive along the river to Oppenheim, a small town surrounded by vineyards, but also where the 6th Armored (and a lot of other units) crossed the Rhine. There's a very nice, rarely visited, memorial there. You can cross there, if the ferry is running, but it's probably faster to find a bridge or just head to Frankfurt.

From Frankfurt your path should be to Bad Neuheim, Alsfeld, Kassel, Mulhausen, and Buchenwald. Part of this your father participated in. I don't know this as well, but it's not hard to plan a route along those lines. The armies were moving pretty quick at this stage, so I'm not sure what you'll find; certainly none of the fortifications like those along the Saar or Rhine.

A few years ago I was researching a relative's WWI service and wanted to visit the places in France where he fought and was injured. I found out that there are specialized guides in Europe who can take you to the places they fought in, so I hired one for a day. It worked out great because the guide had a great deal of knowledge about the exact battle sites and where each side was positioned, the reserve areas, field hospitals, etc. There are guides who do similar things with WW2.

Maybe contact the 6th Armored Division Association or similar WWII research groups? Some members have done staff rides or battlefield tours.