I am looking at a flights that involve a 20 hour layover in Munich. We'd arrive in Munich at 5:10 PM and fly out the next day at 3:35 PM. Would it be worth killing an evening and morning in Munich? Is it hard to get to the City Center from the airport?

It is simple to get to the center of Munich from the airport by train, and you have plenty of time to enjoy an evening and morning there. There are 2 lines (S1 and S8) that you can take. The train takes about 45minuntes and trains run every 10 to 15min or so. No advance purchase required. Go for it.

Agree with J62 - very easy and very worth the effort for such a long layover. If this trip is happening within the next few weeks, the Christmas Markets will open around November 21 and will run through Dec 24.

When? If these flights are months into the future, flight times will likely change.

We had a slightly shorter layover and stayed in nearby Freising. We had a relaxing evening, a very nice dinner and a short walk around the town in the morning. Hotel/airport shuttle made it easy.

https://bayerischerhof-freising.de/en/