"Berlin Private Tours" is the company we hired for two days of sightseeing in and around Berlin. I originally sent Pen, the owner, a long list of what I wanted to see. She very tactfully pointed out that my list was completely unrealistic for such a short visit, and sent us a proposed itinerary that worked out great for us.
Our private tours came with a guide, Martin Lange, and a driver for an immaculate Mercedes van. Since it was just the 2 of us, Martin could focus on what he knew we wanted to see, what we had never heard of but turned out that we really liked, and on many of the most iconic sites of Berlin. Martin was born in East Germany in the 80's, but I honestly could not hear any German accent in his voice.
He knew we were interested in WW2, so he made time for us to see the house of the Wannsee Conference, the exterior of Cecilienhof Palace in Potsdam (interior closed for renovation), and a few other sites we had never heard of. We didn't have to worry about getting lost or taking too long at any one location. I never imagined that we could see so much without ever feeling rushed, and not getting frustrated with the slowpokes and know-it-alls in the group, since we were the group.
Martin also nailed the regular tour guide things - knowing the perfect spots for photo ops, how to circumvent the bus tour crowds, shortcuts to the next blockbuster site, where the good bathrooms are located, and where it is enough to stop for a quick photo and move on (like Checkpoint Charlie).
I highly recommend Martin and this company. I will be posting a trip report with more details about our visit to Berlin, but I wanted to give a shout out to our guide.