Extra Day in Berlin

Assuming you mean the RS tour of the same name, the page for that tour includes the following (under the "Pre-Tour" tab at the bottom of this [page][1]):

Sightseeing On Your Own

If you arrive in Berlin before your tour begins, use Rick Steves Germany guidebook to get oriented. Ride the public transportation, try out a few words of German (although many locals speak English well), and get over your jet lag with fresh air and exercise.

Here are suggestions for sightseeing in Berlin that we will not be doing as a group (see your guidebook for details): Jewish Museum; Gemäldegalerie; Museum of the Wall at Checkpoint Charlie; Potsdamer Platz; Gendarmenmarkt; Reichstag Dome. If you'd like to visit the Reichstag Dome, you must make advance reservations. The best time to visit is pre-tour or after 3 p.m. on Day 2 or Day 3.
erlin-prague-vienna

Go to Ravensbruck Concentration Camp. Visit Track 17, go to the Wannsee Villa. Go on an alternative walking tour, graffiti or bunkers, or Jewish Berlin.

Hi,

Since you are arriving a day earlier in Berlin, you might want to skip Berlin that day and take the S-bahn or regional train to Potsdam, get off at Potsdam Hbf. The Tourist Office is on the top floor, or you can board one of the tours as you exit from the train station, can't miss them. After the tour, ie, the bus brings you back to Potsdam Hbf, you can walk in the Innenstadt (centre ville) of Potsdam, very nice and interesting culturally/historically.

If you're into the history in Berlin and if you arrive on a Saturday morning, the German History Museum (DHM) on Unter den Linden, a few mins from the Brandenburg Gate, has its film showings, (Sunday too), which you might want to check out.

I would also say to visit House of the Wannsee conference , easy to do by public transport (and it is free to get in) you could also manage to visit track 17 as you may actually have to pass nearby depending what S bahn you take to Wannsee