From airport Berlin-Tegel
Take the express bus X9 (in front of the airport) to "Zoologischer Garten" (Bahnhof Zoo). Change to the S-Bahn. You can take all trains to the east (e.g. Ahrensfelde, Schönefeld, Erkner,...). Leave at "Friedrichstrasse". Hotel "Unter den Linden" is in walking distance (see map). For the other hotels, take a taxi (about 5 Euros), but you can also walk (15 minutes, see map).
A taxi from Tegel to your hotels is about 25-30 Euros.
From airport Berlin-Schönefeld
Take the bus or walk to the S-Bahn station (5 min.). Take the S-bahn S9 in in the direction to "Zoologischer Garten" (Bahnhof Zoo) and leave at "Friedrichstrasse". Further see above.
A taxi from Schönefeld to the city is too expensive.
We wish you a good journey to Berlin!