Looks like we will have a Sunday open from 8:30 am to 3:00 pm. What are your suggestions for “WHAT NOT TO MISS WHILE IN MUNICH?” Our trip is planned for this coming fall, for 2 adults!
It is fall right now so you mean 2020?
Munich is pretty mediocre. You should read up on it there might be something you really want to see
Everyone has their own don't miss places, so without having any idea what you enjoy or like, it is impossible for us to make suggestions. Personally, I would go on a good overview tour of the city and then you get to see most of the highlights of the city in the short time you are there. Try Radius tours or Dark History Tours.
Start by downloading the RS Audio Europe walking tour of Munich now - It gives a very nice overview and with suggestions in the RS Guidebook/other Munich Guidebooks/City Website you can easily fill your time... and pick a nice central place for lunch - ie. Viktualienmarkt (probably).
As has been noted , how you spend your time Is dependent on your interests . Over the last few years , I have made five visits of ten days each time , and love the place . I never run out of things to do , and if I were forty years younger , I would consider living there , or Vienna .
The BMW Museum (next door to the "World") turned out to be one of my favorite places from our 2015 trip to Strasbourg, Munich and Vienna. I thought I was doing my husband a favor by going there, but I think I liked it better than he did! It was like the Tate Modern with cars and motorcycles instead of paintings and sculpture.
Across the street from the BMW Museum/World is the site of the 1972 Olympics. We had some excellent sausage and beer at a casual restaurant on the Olympic grounds, which are now a park.
Sundays in Munich tend to be the days when everything opens later, if it opens at all. Be sure to check the hours when planning.