I have been to Munich numerous times at different times of the year. It is worth a stop for a day or two or three, depending on your interests.

This year I was there for my first Oktoberfest and experienced things I hadn’t before. Dinner reservations were required unless you planned to eat at 5pm or have take out pizza. Public transportation both within the city and to/from the city was filled to capacity. DB trains in and out of the city ran significantly late. Room rates were a minimum of 50% higher than usual, depending on location.

If that doesn’t discourage you, Oktoberfest can be family friendly and fun. The official website will tell you what days of the week and times of the day are expected to be the busiest. Usually, arriving when the gates open and leaving by mid afternoon you’ll avoid the worst crowds. You‘ll even be able to get a table and eat breakfast at some of the beer tents. Non-alcoholic beverages are available. But, public transportation will likely be packed in the afternoon.

While Oktoberfest is free, The Oide Wiesn section costs 4 euro to enter but it is quieter and has activities specifically geared to children. It also has traditional music and dancing throughout the day.

We just left Berlin this morning. Have a few comments. First, you don’t want a car for this trip because you are spending all or most of your time in cities. Second, I too would open jaw your flying
despite your children’s take on flying. We started to take our children abroad when they were barely 8 and 9 and they did fine as long as we did not try to do much each day. Your gc will be about 7 next September and should do ok unless she is has special needs. It’s less than an hour flight between FRA and BER. In fact in order to save a day I would fly through FRA onto either BER or MUC upon arrival. There is a flight about every 2 hours. Keeps you from losing another day to travel. Third avoid Munich during the Oktoberfest.
Hotels are very expensive and I don’t see a child getting anything from it. Hotels are also expensive in Berlin during the marathon too with over 55000
runners. Fourth you could consider renting a car in Munich to explore Bavaria and its alps if you can find the time. Consider doing Salzburg as a long day trip from Munich. Every time you move you lose most of a day. Doing the open jaw, flying onward from FRA the day of arrival opens up 2 free days. Do read guide books to give you a better idea of what your family may like to do.

Hello. I just wanted to pop in and thank everyone for their comments, My family will be together over the holidays and hope to hammer a plan together. I’m sure I will be either back to this thread or starting a new one as we put the details together. Wishing you all a joyous holiday season!

Happy New Year! Your trip sounds wonderful especially that your SIL's sister is running a marathon in Berlin. I'm planning for a 2026 trip to fly into Frankfurt, rent a car and drive through Miltenberg, Rothenberg ob de Tauber, Nuremberg and Munich. Then train up to Berlin and after that we're training to Amsterdam. I want the mix of small quaint Bavarian towns with successively larger cities to get the mix. Very excited for Berlin.

I look forward to seeing your plan before September.