I have a week in Munich in February. Anything one MUST do?
Go to Salzburg and Berchtesgaden !
I think there are few places in Europe that are MUST do. It depends on your tastes and preferences. Some would say Dachau, yet I didn't go there. I enjoyed the tour of Nymphenburg, the Residenz including the treasury and we did the walking tour in the RS guide going into all the churches. We liked the beer halls, especially Ausgustiner just off the Marienplatz.
I agree that Salzburg would be a great place to go. We went in the winter and it was lovely (and cold). In fact, I would cut two nights in Munich and stay those nights in Salzburg.
My favourite parts of my trip to Munich were the beer gardens, swimming in the lakes and a trip to Salzburg however this was in June during a heatwave.
I, too, enjoyed Nymphenburg and the Residenz. There's the Glockenspiel, also, which is fun to see.
I visited in May a few years ago, and things I enjoyed in Munich were the Nymphenburg Palace--lots to explore there, various other buildings on the spread out estate including the wonderful Marstallmuseum--Dachau, and the Alte and Neue (I liked this one the best) Pinakotheks as well as the Pinakothek der Moderne. Exploring the Marienplatz Square happened a few times as well as a couple of meals at the Hofbrauhaus. I made 2 day trips by train during my 6 day stay--to Nuremburg and to a small town called Giengen an der Brenz that is the home of Steiff toys--lifelong collector, they were founded in 1880 and the original factory is there along with a museum. On a Saturday I made the rounds of 3 vintage flea markets. I didn't accomplish quite as much as I had planned due to my lower back going out in spectacular fashion, so there are definitely other museums and sites I would have liked to visit.
Take a day trip to Garmisch-Partinkirchen and enjoy the Alps.
Frauenkirche, Nymphenburg Palace, English Garten, BMV World, Olympic Park, Marien Platz/Glockenspiel at the Rathaus, Viktualienmarkt, climbing the St Peter's Tower are experiences I enjoyed. We also enjoyed waling through Schloss Schleissheim. I don't know if they are MUST dos - it depends on what you want to see/do
Deutsches Museum, definitely. It's on an island in the Isar river. Closest S-Bahn stop is Isartor.
It's not possible to see the whole thing in one day, but maybe hit the high points (aviation exhibit, bridge building exhibit, and model train layout).
The Viktualsmarkt
Deutches Museum and the Alte Pinakothek
City walking tour and a Beer and Brewery Tour-my favorite thing.
Dachau
Englisch Garden even in the winter is nice
The The Munich Documentation Center for the History of National Socialism is a must do. Give yourself at least 2 hours there, maybe more. I spent a month in Germany in the summer of 2023 and the Munich Nazi Documentation center experience was in the top 5 of my many exceptional experiences there. I went there after "touring" Dachau with a private guide which I also recommend in order to get the most out of your visit to Dachau. These two places are not to be missed.
If you don't want to train all the way to Salzburg (which you should), prien am chiemsee is also recommended as a daytrip by train and boat.
You must go to a bier garden as that is the origin of such. At that scale.
If you are speaking about 2024, February is Carnival. Simply Munich lists a variety of events taking place. Since I did not get to visit for the Christmas season, I have been contemplating a Fasching alternative. Really would like some yummy Krapfen.
If the week is late in the month, go to one of the stark (strong) beer festivals https://www.augustinerkeller.de/de/veranstaltung/starkbierfest. Not anywhere near as big as Oktoberfest, but should be great fun.