13 nights in February

I'm surprised to see Wuerzburg as your first destination if it's not a place you're eager to revisit.

I'd probably opt for a direct train ride to Nuremberg for those first 3 nights instead. If you're willing to travel the 1.5 hours it takes to reach W'burg, why not just stay on the train to Nuremberg? That would be roughly 2.25 hours on the ICE.

Alternatively, you might want to choose the Bavarian city of Aschaffenburg in place of W'burg for that first night. It's on that same railway that Wuerzburg is on, but you'd get there sooner. The direct ICE from FRA gets you to A'burg in 1 hour. The next day, it's another direct ICE train ride to Nuremberg, just 1.5 hours. Consider the "Hotel Zum Goldenen Ochsen am Schlossgarten" in A'burg, which is close enough to the train station.

(continued...)

Bamberg: I sent you first to NUREMBERG instead simply because in addition to the Documentation Center, Nuremberg is blessed with many INDOOR options for you, including many museums of different types which have no connection to WW II... So I see it as a solid base town for you for perhaps 4-5 days, during which you could easily make the 45-minute train ride to Bamberg on a DAYTRIP instead of having to change hotels... and if you really need an additional day for Bamberg, then make a 2nd day trip there. Explore those indoor options in Nuremberg here:

https://tourismus.nuernberg.de/en/discover/museums/

Nuremberg is also full of restaurants and pubs, many nice hideouts when the winter weather is working against you:

https://www.tripadvisor.com/FindRestaurants?geo=187310&sort=FEATURED&establishmentTypes=10591&broadened=false

I rave about Frankfurt all the time on here. Tons of historic sites to see, dozens of museums, lots of parks and nature, though in Winter not so much fun.
What period of history do you like or anything specific?
There are also lots of fantastic towns to visit that are near-by - Büdingen, Bad Homburg, Limburg, Marburg, Seligenstadt, Idstein, Michelstadt, Mainz, Eltville. All within 1 hour by train from Frankfurt.

I just shuddered at the sight of so much time allocated to Garmisch-Partenkirchen!

You seem to be just wandering around the areas you've already got some knowledge about without being that enthusiastic about any of it. Try going somewhere in a different direction. Head south from Frankfurt Airport to somewhere near to Freiburg in Breisgau, we can discuss the benfits of exact areas and the Konus card later. Freiburg is a nice medium size city with an interesting core and access to both mountain tops (you don't have to walk there!), mountain lakes, areas which I have known to be above the low cloud of winter and the city of Basel in Switzerland.

Then move east to another base, route/mode to be decided but possibly Konstanz and the Bodensee (more of an inland sea than lake). Not big but useful for late afternoon, dinner, overnight and maybe a second night. Then move from here, possible short cut via Switzerland, and on to Innsbruck via the Arlberg route. After a few nights there up to Mittenwald (not Garmisch!!) before final run to Munich

Thanks!! I wasn’t too sure about GaPa BUT we were in Switzerland (Lucerne) this year and want to see more alps. Would Mittenwald for a few days be ok?

I’m going to rethink things. Konstanz and the Bodenese are places I’ve wanted to go and my husband keeps mentioning the Black Forest, so Freiburg would be good. -

You are going to Innsbruck, that is a nice place to visit, but consider skipping and adding Salzburg.