Originally Posted by EZETravel
Little of all, all you can do with kids.
Depending on the weather, there are several nice areas to have a walk like Savignyviertel, Alexanderplatz, etc. You should check http://www.berlin.de/international/index.en.php
for current events. Maybe there is something interesting for you.
You could visit the "Reichstag" http://www.bundestag.de/htdocs_e/index.html
but AFAIK you have to book it in advance. The area is generally intersting and you can see the Brandenburg Gate and "Unter den Linden" (Area of most international embassies and "Friedrichstraße" with the former Checkpoint Charly. http://en.wikipedia.org/wiki/Checkpoint_Charlie
I personally like science and would strongly recommend the "Museum of Natural History" http://www.naturkundemuseum-berlin.de/en/
There you can find the original (first found) fossil of the Archaeopteryx and many other intersting things. Maybe it is a nice thing in case of bad weather.
In general, the sighst listed in tripadvisor could be a good start. http://www.tripadvisor.com/Tourism-g...Vacations.html
If you want to see a bit of the city center without paying too much: The bus line 100 connects Alexanderplatz with the government area. You will come across many sights and if you see something interesting, just leave the bus and have fun. http://www.bus100.de/
If you have any further question I will try to help.