Arrived at MUC at around 7:45AM and got took the 35-minute S-bahn ride to the Hilton City (Rosenheimerplatz stop if I recall). Got to the Hilton City at 9:00AM. Checked in but no rooms were available, so I left my bags with the bellman and went back onto the S-bahn and took the 3-minute ride to Marienplatz to walk around. You could easily kill three hours doing a walking tour of the Old Town. My room was available by the time I returned at 12 noon (but they had told me that 12 noon would be fine earlier in the AM).