Now you are making me think, as you seem to be the Munich/Sixt expert ...maybe I should try to change the location for delivery of the car. I also chose Arnulfstr because it was not far for me and I could get a ride with my luggage. I am staying in Isarvorstadt, Otto-Hahn Ring looks some distance away...I would not wish to take the luggage that far on a bus...but maybe I could use a taxi or pick up the car and drive back to get my things. Do you think Sixt would be accommodating to this change? The rental is still a few months in advance.

Or maybe I am thinking about this too much...I just want things to go as good as possible.

I have another question - my flight has been changed and now departs from STR before the opening hours of the Sixt office there. Do you have any experience dropping off a car there when the desk is closed? Or should I try to do it late the previous evening? I don't have any rental experience at that airport.