Your experience with traveling there makes a huge difference.
What do recommend for us first time visitors to Berlin?
If you are a plan-a-holic as I am. I am sure you have read all the guide books and check out all the web sites. I am sure everyone has their own favorite things to do. Ill just give you our take on Berlin. I have to warn you. I think we enjoyed everything. We arrived in Berlin with very low expectations and were more than pleasantly surprised with the city and people.
First and foremost, dont be afraid to use the metro system. It is reliable, fast and safe. A family of 5 can get an all day pass for zones A & B for around 17 Euros.
Of course if you are a history buff you have to see Brandenburg Gate, the Berlin Wall, and Memorial to the Murdered Jews of Europe, Checkpoint Charlie and Topography of Terror. Checkpoint Charlie is a bit of a tourist trap, but we are tourist after all. For a few Euros you can have your picture taken with an actor playing a soldier. My kids got a kick out of this. The Topography of Terror is the rubble site of the command center of Hitlers Gestapo and SS. They were working on an exhibit there last summer. We will probably return to see if it is now open. Around the city you may see on the ground a trail of bricks. These bricks were put in place to represent where the wall once stood.
If you are in to seeing opulent palaces then Potsdams Palaces is the place for you. There are several buildings/palaces, each one more ornate than the other. The grounds are fabulous as well. It is about 20minutes outside of Berlin on the regional train.
If you prefer to take the metro and walk a bit, you can explore the Charlottenburg Palace Area. It is equally as nice and the garden is beautiful.
We visited a number of churches, Kaiser Wilhelm Memorial Church, Berlin Cathedral, Marien Church. Each one was worth seeing for their own reasons.
Outside of Berlin about 45 minutes by bus or train is the Sachsenhausen Concentration Camp in Oranienburg, Germany. Im sure that everyone has their own thoughts on visiting this type of place. Ill just say it left our family speechless. If you are interested, to get there from Berlin, take S-Bahn N°1 or the regional train bound for Rostock (one leaves from Zoologischer Garten, platform 3, at 10:30am) to Oranienburg. From Oranienburgs station, you can catch bus N°804 to the camp (Gedenkstätte stop), or walk for 25 minutes. Turn right onto Stralsunder Straße, right onto Bernauer Straße, left onto Straße der Einheit, and right onto Straße der Nationen.
There are many great buildings and other sites to see like the Reichstag Building, the TV tower, Gendarmenmarkt, the Victory Column, and the Opera House.
We plan on exploring the Pergamon and the Neues Museum and taking the metro out to the Olympic Stadium.
We also found an area where many locals go to dine. It is near The Church of St. Nicholas (Germ. Nikolaikirche). The church is located in the eastern part of central Berlin, the borough of Mitte. The area around the church, bounded by Spandauer Straße, Rathausstraße, the River Spree and Mühlendamm, is known as the Nikolaiviertel 'Nicholas quarter'
I know I havent been very specific on any of the sights. I recommend doing your homework and pick a few that interests your family. We stumbled our way across the city and saw many things. It was fun taking the metro and going at our own pace. If you download the metro map and purchase a city map, you will have no trouble exploring on your own. You will most like save a bundle of $$$ for St. Petersburg!