Berlin Tours

I have been on the Berlin Prague Vienna tour and can give you ideas about what we did in our free time in Berlin.
We visited the Jewish Museum, very interesting.
We went to the Museums on Museum Island - you may do this on your tour, I'm not sure. But we liked the museums very much.
We went to the Gemaldegallerie over by the newer part of Berlin, sorry, my memory escapes me. There were 2 Vermeers in this amazing museum!
We went to a performance at the Berliner Komische Oper, a performance hall with a variety of musical and dramatic shows.
We walked a lot through Prenzlauer Berg, where our hotel was, in former East Berlin.
I would love to return to Berlin.
Oh, some of our tourmates got tickets in advance to Reichstag to climb to the top. We didn't do this.
I don't think we bought advance tickets for the things we did.

I had a couple of extra days last year after my Best of Germany tour ended in Berlin. You can get an advance reservation for the Reichstag to climb to the top - it was very worthwhile and saved standing in line. I also took one of the 1 hour boat cruises on the Spree river, which was relaxing and gave a nice different view of the city. I agree that you can go to all the Museums on Museum island on your own. I went to the German History museum and found it very interesting. The Topography of Terror exhibit is very worth your time - it's a fascinating compilation of photos from WWII and afterwards. Easy to walk to it. Also spend some time exploring the city and the many memorial sites and parks. It's an easy train ride to Potsdam, and then a pretty short walk into town. Go through your guide books and do some online searching and you'll find a ton of things to do in Berlin and the surrounding area. It's a fascinating city and you can easily explore it on your own with a map (or map app on your phone). Enjoy it, and take some time to savor a beer and watch the world go by.

Yes on going to Potsdam. You can independently take the S-Bahn from Berlin Hbf, The direction/terminus is Potsdam Hbf.

The top floor of Potsdam Hbf is also the location of the Tourist Office and Reisezentrum...a very nice and elaborate train station. Potsdam is one of my favourite towns in Germany.

Outside of Potsdam Hbf are various tour companies trying to get you to go with them instead of their competitors.

The S-Bahn runs every 10 mins, not only from Hauptbahnhof, but also from - among others - Ostbahnhof, Alexanderplatz, Friedrichstrasse and Zoologischer Garten. Pick the most practical station. You need a so-called ABC-ticket at the most agreeable cost of EUR 3,40 (single) or EUR 7,70 for a day pass (Tageskarte). It is a pleasant walk from Potsdam Hbf to the centre and further on to the park and palaces.

Added:
I have no experience with that trip, but the Glienicker Brücke is easily reached from Potsdam with tram #93, which runs every 20 mins. It has a stop at Potsdam Hbf (where you get off the S-Bahn), but also in the city centre. The Tourist Office can undoubtedly tell you the stops. The tram is included in the day pass.

Thanks to you all for the wonderful information.

mm,

I've used THIS tour firm in Berlin and very pleased with the tours they provided. They often use public transit to get to outlying areas, so the cost is reasonable. They also have tours for Potsdam.

Is the Pergamum Museum open now? If it is, don't miss it.