We opted for an overnight SPB tour in Berlin as it's a very long drive from Warnemunde (3-3.5 hours). There were 8 of us. On day one we went to the must-sees in Berlin (Brandenburg Gate, Reichstag, site of Hitler's bunker, Holocaust Memorial, Pergamon Museum, remains of the Wall, Checkpoint Charlie, etc. A lot was necessarily packed into the day. Being a museum junkie, I would have wandered for hours (days?) on Museum Island had I been able. The tour focused on what most people want---WWII history---though I would have enjoyed a bit more about Prussia. We stayed at the Swissotel (quite reasonably priced, very good service and a fine breakfast). Day 2 ---we were off to Potsdam to visit Sans Souci and the site of the Potsdam Treaty signing. Both were enjoyable. We had 2 different guides, both expats and well educated in German history. One caution---even though all the materials from SPB say you can use a credit card, they claim their machine has been broken for a year and you will have to venture off for an ATM (could be quite a problem, as the 2 day tour cost for a couple exceeds the daily limit most banks put on ATM withdrawals). All in all, I'm glad we did this and I can cross Berlin off my bucket list.