Berlin - Private or group tours before or after RS self guided tours

I think a guided tour is 10 times better than any kind of audio tour or guidebook tour. You have a live guide who can answer questions, that is a professional at what they do, and can tell you about current events that are happening or new things that have been found. Berlin is a city in flux and I don't think a guidebook tour can keep up with all the changes.

For private tours, I would go with "Jeremy the Berlin Expert" and for group tours, "Insider Tours". They are my go-to tours every time I visit Berlin.

I'm a huge fan of private tours. In Berlin, my go-to guy is Robert Sommer. He is a native of (East) Berlin and was the 15-year-old son of a high-ranking East German bureaucrat on Nov 9, 1989, the night the Berlin Wall "fell." He is a former punk rocker and post-unification squatter who ended up earning a PhD in history with a thesis that explored prostitution in WWII concentration camps. He contributed to the exhibition at Ravensbrück concentration camp. I'm sure he would give you a great WWII tour in Berlin. I have done many well-off-the-US-tourist-beaten path activities with Robert, including visiting a forest and field that were used for training WWI and WWII soldiers; deserters and those who "hurt morale" were executed as traitors in the woods; these soldiers were memoralized by a very interesting art installation. We did a day trip to Seelow Heights (site of large battle between Germans and Russians) and Küstrin, a German town that was mostly wiped out by the Russians and stands eerily empty and overgrown -- reminiscent of Pompeii. I've done a lot of Cold War things with him, too, including going down into bunkers used by the Soviets to store nuclear warheads. Robert is a quite fascinating guy who not only knows Berlin history, but has lived it and is willing to share his experience.

WWII history relating to Berlin

What do you mean by this? Because my answer to your original question will depend on this answer.

• Combat places and weapons
• Nazi terror regime
• Holocaust

The VisitBerlin page gives a short overview of National Socialism and II. World War.

At very rare places you can still find scars from combats, e. g. a hole of a shot from a likely Russian tank through a steel girder of a S-Bahn bridge (photo from Leibnizstrasse).

For interested people in these parts of history I recommend also to search and surf the federal picture archive.

Forgot to leave Robert's website: http://thetrueberliner.com/

He is willing to create a tour around pretty much anything you want to see. Most recently, I gave him some concepts for a tour about the former East Berlin/East Germany (the latter was abbreviated DDR), and he crafted a tour he called "The DDR: From the Dream of Communism to Neonazi Violence." Robert discussed the DDR’s use of art, architecture and open space as means to promote community in the area around Alexanderplatz and along Karl Marx Allee. We viewed a couple of the few remaining squatters' buildings in the old East Berlin. We went to Marzhan to see a large residential complex built by East Germany and to hear Robert's stories of growing up there, including fights/wars between neonazis and punk rockers. We finished up the day with a visit to Alt-Marzahn village, a medieval village in the midst of the larger surrounding development. We had a late lunch at the village's butcher shop, which also had some prepared foods, many of which were old East German staples. It was really cool to do a tour like this... with a local... who personally experienced pretty much everything that was discussed... and shared his personal stories.

I realize I sound like an excessively-enthusiastic fanboy or maybe even a "plant." I talk up Robert because I honestly think no guide in Berlin offers a better experience to the intellectually curious who visit Berlin. I will venture to say that no other guide in Berlin has a story about his father meeting Kim Jong Un in Pyongyang at an international Communist Youth meeting, where he was offered to have one wish granted by the North Korean leader due to the impressiveness of East Germany's exhibition. The audacity of his dad's wish drew a gasp from the crowd... but was granted.

We plan on starting in Berlin, and I was thinking of staying there 4
nights before moving on.

It all depends on your interests and priorities, but there are an enormous number of things to see. I love Berlin and have spent 58 nights there since 2015. Hopefully, I will return in late August/early September for more. One forum member apparently went there expecting to finding "the real Germany" and didn't like it. Expect a German take on an international multicultural city with access to a lot of German history.

I’ll echo Dave here - we used Robert Sommer for a day tour as well. He’s awesome. We had great conversations with him. We learned a lot of about planned WW2 sites, but we went way off on a tangent hearing tons about his fascinating upbringing as the child of an East German government employee and that was my favorite part of our conversations. We would absolutely tour with him again.

As child of Berlin I think that the story of my city is too manifold to be told by one person only - with all respect for Robert who seems to do a real great job. Also the East German cold war times are worth to be told also by all the victims of the system too. At the same time regime supporters were enjoying their Sunday breakfast, others suffered and died in Stasi prisons - often without a sentence of an official court (not a Stasi court) and unmentioned, relatives uninformed.

Back to OP's queston:
Especially for the people interested in the time 1933-1945 there are a lot of specialized places. I recommend to use the guides of these specialized sights because they know so many details of this topic, e. g. former concentration camp Sachsenhausen at Oranienburg. And always think of the other side of a slice of history: if you think of Nazi terror, also remember the resistance which also has a place in Berlin.