Madrid airport to city

Thank you to everyone for such useful advice. It was very informative. I tried to take the Aerocity shuttle without a reservation and was told that it is sometimes possible, depending on whether a driver is available, but one wasn't at that time! So I took the Metro and found it was fine for me. However, as MadridMan said, I think if you have lots of luggage or are a bit unfit, the stairs could be a problem.

Thanks again for the advice!

Glad it worked out for you.